#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	string s;
	cin>>n>>s;
	for(int i=0;i<s.length();i++)
	{
		if(s[i]=='z')
		s[i]='a'+n%26-1;
		else
		s[i]=s[i]+n%26;
	}
	cout<<s;
	return 0;
}