#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>
#include <random>
#include <chrono>
#include <cassert>
#include <tuple>
#include <utility>
using namespace std;
int main() {
	string s;
	cin >> s;
	string hoge = "yukicoder";
	for (int i = 0;i < s.length();++i) {
		if (s[i] != hoge[i]) {
			cout << hoge[i] << endl;
			return 0;
		}
	}
}