#include <bits/stdc++.h>

using namespace std;

#define INF 2000000000
#define MOD 1000000007
typedef long long ll;
typedef pair<int, int> P;


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

	int i = 0;
	for (i = 0; i < s.size(); i++) {
		if (s[i]=='?') {
			break;
		}
	}
	cout << org[i] << "\n";
}