#include<stdio.h>
#define N 50
int main(void)
{
	char ch[N];
	int n;
	char ich[N];
	scanf("%d\n%s", &n, ich);
	for(int i = 0; ich[i] != '\0'; i++)
	{
		if(ich[i] + n <= 122)
		ch[i] = ich[i] + n;
		else
		ch[i] = 'a' + (n -1) - ('z' - ich[i]);
	}
	printf("%s", ch);
	return 0;
}