diff --git a/old_homework/homework_11.30.cpp b/old_homework/homework_11.30.cpp
new file mode 100644
index 0000000..43fe2ea
--- /dev/null
+++ b/old_homework/homework_11.30.cpp
@@ -0,0 +1,52 @@
+#include<iostream>  //字母位移
+
+using namespace std;
+
+/*
+int main(){
+    char CIN,COUT;
+
+    cin >> CIN;
+
+    int CIN2 = CIN+=3;
+    
+    COUT = CIN2;
+
+    cout <<COUT;
+    return 0;
+}
+
+
+int main(){
+    while (true)
+    {
+        char letter;
+        int n = 3;
+
+        cin >>letter;
+        
+        if (letter >= 'A' && letter <= 'Z') {
+            char new_letter = (letter - 'A' + n) % 26 + 'A';
+            cout << new_letter<<endl;
+        }
+    }
+    
+    return 0;
+}*/
+
+int main(){
+    while (true)
+    {
+        char ch1,ch2;
+
+        int n = 3;
+
+        cin >>ch1;
+        ch2 = ((ch1 -65)+n) %26 +65;
+    
+        cout <<ch2<<endl;
+    }
+    
+    
+    return 0;
+}
\ No newline at end of file