#include <bits/stdc++.h>

using namespace std;

int main(int argc, char **argv) {
	char S[20];
	scanf("%s", S);
	const char *y = "yukicoder";

	for (int i = 0; i < strlen(y); i++) {
		if (S[i] != y[i]) {
			printf("%c\n", y[i]);
			return 0;
		}
	}
	return 0;
}