#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
#define ALL(x) (x).begin(), (x).end()
#define REP(i ,n) for(int i = 0; i < (int)(n); i++)
#define pb push_back
#define mp make_pair
typedef vector<int>vint;
typedef vector<ll>vll;
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename A,typename B>inline bool chmin(A &a,const B &b){if(a>b){a=b;return true;}else{return false;}}
template<typename A,typename B>inline bool chmax(A &a,const B &b){if(a<b){a=b;return true;}else{return false;}}

int main()
{
    string S;
    cin >> S;
    REP(i,S.size()){
        if(S[i] != (char)(i+'a')){
            cout << (char)(i+'a') << "to" <<S[i] << endl;
            break;
        }
    }
}