/*
 Author: 曹北健
 Result: AC Submission_id: 5469064
 Created at: Thu May 25 2023 20:49:51 GMT+0800 (China Standard Time)
 Problem_id: 6933   Time: 9 Memory: 1600
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <ctype.h>
#pragma warning(disable:4996 6031)
int main(){
#ifdef _DEBUG
    freopen("../../input.txt", "r", stdin);
#endif // _DEBUG
    char s[256] = { 0 };
    long long b[256] = { 0 }, a[256] = { 0 };
    int i, n;
    long long k, m = 1;
    scanf("%lld%s", &k, s);
    for(i = 0; s[i]; i++){
        a[i] = s[i] - 'a';
    }
    n = i;
    b[0] = (a[0] + k * (m - 13)) % 26;
    if(b[0] < 0){
        b[0] += 26;
    }
    for(i = 1; i < n; i++){
        m = b[i - 1];
        b[i] = (a[i] + k * (m - 13)) % 26;
        if(b[i] < 0){
            b[i] += 26;
        }
    }
    for(i = 0; i < n; i++){
        putchar('a' + b[i]);
    }
    putchar('\n');
#ifdef _DEBUG
        freopen("CON", "r", stdin);
    system("pause");
#endif // _DEBUG
    return 0;
}