diff --git a/bin/Main.class b/bin/Main.class
index 3ec49de..5ecfc8f 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 2eeb10c..117df1e 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 17094df..8ec5a42 100644
--- a/exercise/src/Main.java
+++ b/exercise/src/Main.java
@@ -1,16 +1,48 @@
 import java.util.Scanner;
+import java.util.HashMap;
+import java.util.Map;
+import java.math.BigInteger;
 
 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(' ');
+        if (!in.hasNext()) {
+            System.out.print("no");
+            in.close();
+            return;
         }
-        System.out.println(sb.toString());
+        int n = Integer.parseInt(in.next());
+        if (n <= 0) {
+            System.out.print("no");
+            in.close();
+            return;
+        }
+        
+        Map<String, Integer> cnt = new HashMap<>();
+        Map<String, Integer> first = new HashMap<>();
+        String best = null;
+        int bestCount = 0;
+        int bestIdx = Integer.MAX_VALUE;
+        int idx = 0;
+        while (idx < n && in.hasNext()) {
+            String raw = in.next();
+            String norm = new BigInteger(raw).toString();
+            int c = cnt.getOrDefault(norm, 0) + 1;
+            cnt.put(norm, c);
+            if (!first.containsKey(norm))
+                first.put(norm, idx);
+            int fi = first.get(norm);
+            if (best == null || c > bestCount || (c == bestCount && fi < bestIdx)) {
+                best = norm;
+                bestCount = c;
+                bestIdx = fi;
+            }
+            idx++;
+        }
+        if (best == null)
+            System.out.print("no");
+        else
+            System.out.print(best);
         in.close();
     }
 }
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day40/第一题/Main.java b/作业/作业/刘航宇-day40/第一题/Main.java
new file mode 100644
index 0000000..0f71f1e
--- /dev/null
+++ b/作业/作业/刘航宇-day40/第一题/Main.java
@@ -0,0 +1,22 @@
+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(" ");
+        String best = "";
+        int max = -1;
+        for (String w : words) {
+            int end = w.length();
+            while (end > 0 && !Character.isLetter(w.charAt(end - 1))) end--;
+            String t = w.substring(0, end);
+            if (t.length() > max) {
+                max = t.length();
+                best = t;
+            }
+        }
+        System.out.println(best);
+        in.close();
+    }
+}
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day40/第一题/image.png b/作业/作业/刘航宇-day40/第一题/image.png
new file mode 100644
index 0000000..5f5af48
Binary files /dev/null and b/作业/作业/刘航宇-day40/第一题/image.png differ
diff --git a/作业/作业/刘航宇-day40/第三题/Main.java b/作业/作业/刘航宇-day40/第三题/Main.java
new file mode 100644
index 0000000..2e5cc36
--- /dev/null
+++ b/作业/作业/刘航宇-day40/第三题/Main.java
@@ -0,0 +1,47 @@
+import java.util.Scanner;
+import java.util.HashMap;
+import java.util.Map;
+import java.math.BigInteger;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        if (!in.hasNext()) {
+            System.out.print("no");
+            in.close();
+            return;
+        }
+        int n = Integer.parseInt(in.next());
+        if (n <= 0) {
+            System.out.print("no");
+            in.close();
+            return;
+        }
+        Map<String, Integer> cnt = new HashMap<>();
+        Map<String, Integer> first = new HashMap<>();
+        String best = null;
+        int bestCount = 0;
+        int bestIdx = Integer.MAX_VALUE;
+        int idx = 0;
+        while (idx < n && in.hasNext()) {
+            String raw = in.next();
+            String norm = new BigInteger(raw).toString();
+            int c = cnt.getOrDefault(norm, 0) + 1;
+            cnt.put(norm, c);
+            if (!first.containsKey(norm))
+                first.put(norm, idx);
+            int fi = first.get(norm);
+            if (best == null || c > bestCount || (c == bestCount && fi < bestIdx)) {
+                best = norm;
+                bestCount = c;
+                bestIdx = fi;
+            }
+            idx++;
+        }
+        if (best == null)
+            System.out.print("no");
+        else
+            System.out.print(best);
+        in.close();
+    }
+}
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day40/第三题/image.png b/作业/作业/刘航宇-day40/第三题/image.png
new file mode 100644
index 0000000..ef9db86
Binary files /dev/null and b/作业/作业/刘航宇-day40/第三题/image.png differ
diff --git a/作业/作业/刘航宇-day40/第二题/Main.java b/作业/作业/刘航宇-day40/第二题/Main.java
new file mode 100644
index 0000000..1d6cd84
--- /dev/null
+++ b/作业/作业/刘航宇-day40/第二题/Main.java
@@ -0,0 +1,27 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        int n = Integer.parseInt(in.nextLine().trim());
+        StringBuilder out = new StringBuilder();
+        StringBuilder line = new StringBuilder();
+        int count = 0;
+        while (count < n && in.hasNext()) {
+            String w = in.next();
+            count++;
+            if (line.length() == 0) {
+                line.append(w);
+            } else if (line.length() + 1 + w.length() <= 80) {
+                line.append(' ').append(w);
+            } else {
+                out.append(line).append('\n');
+                line.setLength(0);
+                line.append(w);
+            }
+        }
+        if (line.length() > 0) out.append(line);
+        System.out.print(out.toString());
+        in.close();
+    }
+}
\ No newline at end of file
diff --git a/作业/作业/刘航宇-day40/第二题/image.png b/作业/作业/刘航宇-day40/第二题/image.png
new file mode 100644
index 0000000..0755f7e
Binary files /dev/null and b/作业/作业/刘航宇-day40/第二题/image.png differ
diff --git a/作业/压缩包/刘航宇-day40.zip b/作业/压缩包/刘航宇-day40.zip
new file mode 100644
index 0000000..2617846
Binary files /dev/null and b/作业/压缩包/刘航宇-day40.zip differ