#include<iostream>
using namespace std;
int main(){
	int n;
	char a[100];
	cin>>n>>a;
	int i=0;
	while(a[i]!='\0'){
		if(a[i]=='z'){
			a[i]=='a';
		}else{
			a[i]=(a[i]-'a'+n)%26+'a';
		}
		i++;
	}
	cout<<a;
	return 0;
}