C++ :

#include <iostream>
using namespace std;

int main() {
    char inputChar;
    int key;
    cin >> inputChar;
    cin >> key;

    char encryptedChar = inputChar + key;  // 加密字符
    cout << encryptedChar << endl;

    char decryptedChar = encryptedChar - key;  // 解密字符
    cout << decryptedChar << endl;

    return 0;
}