#include<iostream>
 using	namespace std;
 #include<string>
 int main() {
 	int a;
	cin>>a; 
  	string s;
  	cin>>s;
  	a=a%26;
	for(int i=0;i<s.size();i++){
     s[i]=s[i]+a;
     if(s[i]>'z') s[i]=s[i]-26;
	  }
	  cout<<s;
  }