#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
using namespace std;

int max(int a, int b) {
	int x = (a > b) ? a : b;
	return x;
}

int min(int a, int b) {
	int x = (a < b) ? a : b;
	return x;
}

int main() {
	string s;
	cin >> s;
	string ss = "yukicoder";

	for (int i = 0; i < 9; i++) {
		if (s[i] != ss[i]) {
			cout << ss[i] << endl;
			break;
		}
	}
	
	return 0;
}