#include <iostream>
#include <string>

int main() {
	std::string s;
	std::cin >> s;
	for (int i = 0; i < 26; ++i) {
		if (s[i] != 'a' + i) {
			char x = 'a' + i;
			std::cout << x << "to" << s[i] << std::endl;
			return 0;
		}
	}
}