#include <stdio.h>

int main() {
	int x; char arr[100] = { 0 };
	scanf("%d", &x); 
	scanf("%s", arr);
	for (int i = 0; i < 100; i++) {
		if (arr[i] == '\0') { break; }if(arr[i] == 'z') {
			printf("%c", 'a' + x - 1); break;
		}
			arr[i] = (arr[i] - 'a') % 26 + x;
			printf("%c", arr[i] + 'a');
	}
	return 0;
}