//No.494 yukicoder
#include<iostream>
#include<string>
using namespace std;

int main()
{
	string yukicoder = "yukicoder";
	string S;
	cin >> S;
	for (int i = 0; i < S.length(); i++) {
		if (yukicoder[i] != S[i]) {
			cout << yukicoder[i]<<endl;
			break;
		}
	}
	return 0;
}