#include <bits/stdc++.h>
#define rep(i,n) for (int i=0; i<(n); ++i)
using namespace std;
using ll=long long;
int main(){
    string s;
    cin>>s;
    int n=s.length();
    string y="yukicoder";
    rep(i,n){
        if(s[i]!=y[i]){
            cout<<y[i]<<endl;
            return 0;
        }
    }
}