//No.494 yukicoder


#include <bits/stdc++.h>
using namespace std;
namespace
{
int iB;
int iR;
const char lpYuki[] = "yukicoder";

int Chk( char *S )
{
int i;
char C;

	i = 0;
	C = S[ i ];
	while( C == lpYuki[ i ] && C != '\0' ) i++;

	return i;
}

}

int main()
{
int i;
char S[ 20 ];

	cin >> S;

	i = Chk( S );

	cout << lpYuki[ i + 1 ] << endl;


	return 0;
}