#include<bits/stdc++.h>
using namespace std;
int main()
{
	string s;
   int i,len,n;//为什么不能用double型？
	cin>>n>>s;
	len=s.size();
	for(i=0;s[i]!='\0';i++)
	{
		if(n>'z'-s[i])
		s[i]='a'+(n-('z'-s[i]))%26-1;
		else
		s[i]+=n;
		
	}
	cout<<s;
	return 0;