SMMR-T004: Secret (I'm Back)

#include <bits/stdc++.h>
using namespace std;

const int N = 1000;

char str[N + 10];

int main(){

    int len, key;
    scanf("%d%d %s", &len, &key, str);

    for(int i = 0; i < len; ++i){
        char c = str[i];
        if('A' <= c && c <= 'Z'){
            int tmp = (c - 'A' + key) % 26;
            if(tmp < 0){
                tmp += 26;
            }
            str[i] = tmp + 'A';
        } else if('a' <= c && c <= 'z'){
            int tmp = (c - 'a' + key) % 26;
            if(tmp < 0){
                tmp += 26;
            }
            str[i] = tmp + 'a';
        }
    }

    printf("%s", str);

    return 0;
}