拿到了60分，n变大后，就奇怪了

#include<iostream>
using namespace std;
#include<iomanip>
#include<cmath>
#include<algorithm>
#include<stdbool.h>
int main() {    、
  int n;
    cin >> n;
    string  s;
    cin >> s;
    int len = s.length();
    for (int i = 0; i <len; i++) {
        s[i] =s[i]+n;
        while(s[i] > 122)
            s[i] = 96 + s[i] - 122;
    }
    cout << s;
}