#include <iostream>
#include <cstring>
using namespace std;
int main(){
	char b[51],a[51];
	int n;
	cin>>n>>b;
	for(int i=0;i<strlen(b);i++){
		for(int j=1;j<=n;j++){
			b[i]++;
			if(b[i]>'z'){
				b[i]=='a';
			}
		}
		a[i]=b[i];
	}
	cout<<a;
	return 0;
}