#include <iostream>
#include <string>

using namespace std;

int main() {
	string s;
	cin >> s;

	const string t = "yukicoder";

	for (int i = 0; i < s.size(); i++) {
		if (s[i] != t[i]) {
			cout << t[i] << endl;
			break;
		}
	}
	return 0;
}