#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>


typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;



int main()
{

    int Q;
    Q = 1;
    //cin >> Q;
    
    
    while (Q--) {
        string p;
        cin >> p;
        string a = "abcdefghijklmnopqrstuvwxyz";

        for (int i = 0; i < a.size(); i++) {
            if (a[i] == p[i])continue;
            cout << a[i] << "to" << p[i];
            return 0;
        }

    }
    return 0; 
}