#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) FOR(i,0,n)
#define repr(i,n) for(int i=(n)-1;0<=i;--i)
#define each(e,v) for(auto&& e:(v))
#define all(v) begin(v),end(v)
#define DUMP(x) cerr<<#x<<": "<<(x)<<endl
#define DEBUG(x) cerr<<#x<<": "<<(x)<<" (L"<<__LINE__<<")"<<endl
using namespace std;
using vint = vector<int>;
using vdouble = vector<double>;
using vstring = vector<string>;
using ll = long long;
template <class T> void chmin(T& a, const T& b) { a = min(a, b); }
template <class T> void chmax(T& a, const T& b) { a = max(a, b); }

int main() {
    const string right = "yukicoder";
    string s; cin >> s;
    rep(i, 9) {
        if(s[i] != right[i]) {
            cout << right[i] << endl;
            return 0;
        }
    }
    return 0;
}