#include <bits/stdc++.h>
#define INF 990000000
//12
using namespace std;

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

string t="yukicoder";
int fl=0;
for(int i=0;i<9;i++){
if(s[i]!=t[i])fl=i;
}

cout <<t[fl]<<endl;




}