#include <iostream>
#include <string>
using namespace std;
int main(void){
    // Here your code !
    string s,d = "yukicoder";
    cin >> s;
    
    for(int i = 0; i < s.size(); i++){
        if(s[i] != d[i]){
            cout << d[i] << endl;
            return 0;
        }
    }
    
}