diff --git a/bin/Main.class b/bin/Main.class
index a68ba83..3ec49de 100644
Binary files a/bin/Main.class and b/bin/Main.class differ
diff --git a/exercise/src/Main.class b/exercise/src/Main.class
index 814daa6..2eeb10c 100644
Binary files a/exercise/src/Main.class and b/exercise/src/Main.class differ
diff --git a/exercise/src/Main.java b/exercise/src/Main.java
index 412c35e..17094df 100644
--- a/exercise/src/Main.java
+++ b/exercise/src/Main.java
@@ -3,8 +3,14 @@ import java.util.Scanner;
 public class Main {
     public static void main(String[] args) {
         Scanner in = new Scanner(System.in);
-        int n = in.nextInt();
-        System.out.println(n % 3 == 0 ? "hua" : "ming");
+        String s = in.nextLine();
+        String[] words = s.split(" ");
+        StringBuilder sb = new StringBuilder(s.length());
+        for (int i = words.length - 1; i >= 0; i--) {
+            sb.append(words[i]);
+            if (i > 0) sb.append(' ');
+        }
+        System.out.println(sb.toString());
         in.close();
     }
 }
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day38/第一题/Main.java b/作业/作业/刘航宇-day38/第一题/Main.java
new file mode 100644
index 0000000..c11f94d
--- /dev/null
+++ b/作业/作业/刘航宇-day38/第一题/Main.java
@@ -0,0 +1,15 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        String s = in.nextLine();
+        StringBuilder out = new StringBuilder(s.length());
+        for (int i = 0; i < s.length(); i++) {
+            char c = s.charAt(i);
+            if (((int)c & 1) == 1) out.append(c);
+        }
+        System.out.println(out.toString());
+        in.close();
+    }
+}
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day38/第一题/image.png b/作业/作业/刘航宇-day38/第一题/image.png
new file mode 100644
index 0000000..4c2ca35
Binary files /dev/null and b/作业/作业/刘航宇-day38/第一题/image.png differ
diff --git a/作业/作业/刘航宇-day38/第三题/Main.java b/作业/作业/刘航宇-day38/第三题/Main.java
new file mode 100644
index 0000000..40004fc
--- /dev/null
+++ b/作业/作业/刘航宇-day38/第三题/Main.java
@@ -0,0 +1,25 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        int x = Integer.parseInt(in.nextLine().trim());
+        int q = Integer.parseInt(in.nextLine().trim());
+        for (int i = 0; i < q; i++) {
+            String line = in.nextLine().trim();
+            String[] parts = line.split(" ");
+            int p = Integer.parseInt(parts[0]);
+            long t = Long.parseLong(parts[1]);
+            double ans;
+            if (p == 1) {
+                ans = t * (60.0 - x);
+            } else if (p == 2) {
+                ans = 3600.0 * t / (60.0 - x);
+            } else {
+                ans = (12.0 * 3600.0 * 60.0 * t) / x;
+            }
+            System.out.printf("%.2f\n", ans);
+        }
+        in.close();
+    }
+}
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day38/第三题/image.png b/作业/作业/刘航宇-day38/第三题/image.png
new file mode 100644
index 0000000..3c50bfd
Binary files /dev/null and b/作业/作业/刘航宇-day38/第三题/image.png differ
diff --git a/作业/作业/刘航宇-day38/第二题/Main.java b/作业/作业/刘航宇-day38/第二题/Main.java
new file mode 100644
index 0000000..40004fc
--- /dev/null
+++ b/作业/作业/刘航宇-day38/第二题/Main.java
@@ -0,0 +1,25 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        int x = Integer.parseInt(in.nextLine().trim());
+        int q = Integer.parseInt(in.nextLine().trim());
+        for (int i = 0; i < q; i++) {
+            String line = in.nextLine().trim();
+            String[] parts = line.split(" ");
+            int p = Integer.parseInt(parts[0]);
+            long t = Long.parseLong(parts[1]);
+            double ans;
+            if (p == 1) {
+                ans = t * (60.0 - x);
+            } else if (p == 2) {
+                ans = 3600.0 * t / (60.0 - x);
+            } else {
+                ans = (12.0 * 3600.0 * 60.0 * t) / x;
+            }
+            System.out.printf("%.2f\n", ans);
+        }
+        in.close();
+    }
+}
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day38/第二题/image.png b/作业/作业/刘航宇-day38/第二题/image.png
new file mode 100644
index 0000000..e69de29
diff --git a/作业/作业/刘航宇-day39/第一题/Main.java b/作业/作业/刘航宇-day39/第一题/Main.java
new file mode 100644
index 0000000..6ded2ba
--- /dev/null
+++ b/作业/作业/刘航宇-day39/第一题/Main.java
@@ -0,0 +1,11 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        long n = in.nextLong();
+        long ans = n * (n + 1) * (n + 2) / 6;
+        System.out.println(ans);
+        in.close();
+    }
+}
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day39/第一题/image.png b/作业/作业/刘航宇-day39/第一题/image.png
new file mode 100644
index 0000000..73f81c8
Binary files /dev/null and b/作业/作业/刘航宇-day39/第一题/image.png differ
diff --git a/作业/作业/刘航宇-day39/第三题/Main.java b/作业/作业/刘航宇-day39/第三题/Main.java
new file mode 100644
index 0000000..17094df
--- /dev/null
+++ b/作业/作业/刘航宇-day39/第三题/Main.java
@@ -0,0 +1,16 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        String s = in.nextLine();
+        String[] words = s.split(" ");
+        StringBuilder sb = new StringBuilder(s.length());
+        for (int i = words.length - 1; i >= 0; i--) {
+            sb.append(words[i]);
+            if (i > 0) sb.append(' ');
+        }
+        System.out.println(sb.toString());
+        in.close();
+    }
+}
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day39/第三题/image.png b/作业/作业/刘航宇-day39/第三题/image.png
new file mode 100644
index 0000000..519e817
Binary files /dev/null and b/作业/作业/刘航宇-day39/第三题/image.png differ
diff --git a/作业/作业/刘航宇-day39/第二题/Main.java b/作业/作业/刘航宇-day39/第二题/Main.java
new file mode 100644
index 0000000..53a2d05
--- /dev/null
+++ b/作业/作业/刘航宇-day39/第二题/Main.java
@@ -0,0 +1,19 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        String s1 = in.nextLine();
+        String s2 = in.nextLine();
+        int idx = s1.indexOf(s2);
+        String ans;
+        if (idx == -1) {
+            ans = s1;
+        } else {
+            ans = s1.substring(0, idx) + s1.substring(idx + s2.length());
+        }
+        if (ans.length() == 0) System.out.println("null");
+        else System.out.println(ans);
+        in.close();
+    }
+}
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day39/第二题/image.png b/作业/作业/刘航宇-day39/第二题/image.png
new file mode 100644
index 0000000..0b35843
Binary files /dev/null and b/作业/作业/刘航宇-day39/第二题/image.png differ
diff --git a/作业/压缩包/刘航宇-day38.zip b/作业/压缩包/刘航宇-day38.zip
new file mode 100644
index 0000000..a13600f
Binary files /dev/null and b/作业/压缩包/刘航宇-day38.zip differ
diff --git a/作业/压缩包/刘航宇-day39.zip b/作业/压缩包/刘航宇-day39.zip
new file mode 100644
index 0000000..0f67fa9
Binary files /dev/null and b/作业/压缩包/刘航宇-day39.zip differ