ABC146B - ROT N

問題：B - ROT N

#include <iostream>
#include <string>
using namespace std;

#define REP(i, n) for (int i = 0; i < (n); ++i)

int main(void) {
    int n;
    string s;

    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> n;
    cin >> s;
    REP(i, s.length()) {
        s[i] = (n + (s[i] - 'A')) % 26 + 'A';
    }

    cout << s << "\n";
    return 0;
}