#include <stdio.h>
#include <string.h>

int main()
{
    char alphabet[] = "abcdefghijklmnopqrstuvwxyz";

	char	inputText[sizeof(alphabet)];
	scanf("%s", inputText);

	for (int i = 0; i < strlen(inputText); i++) {
		if (alphabet[i] != inputText[i]) {
			printf("%cto%c", alphabet[i], inputText[i]);
			break;
		}
	}
}