#include <iostream>
using namespace std;

char change_register(char n) {
	char a_small = 'a';
	char z_small = 'z';
	char A_big = 'A';
	char Z_big = 'Z';
	if (n < A_big) {
		return n;
	}
	if (n > z_small) {
		return n;
	}
	if (n > Z_big && n < a_small) {
		return n;
	}
	
	char diff = a_small - A_big;
	if (n >= a_small && n <= z_small) {
		return n - diff;
	}
	return n + diff;
}

int main() {
	char n;
	cin >> n;
	cout << change_register(n);
	return 0;
}