#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll=vector<long long>;
template<typename T>T get(){T r;cin>>r;return r;}
template<typename T>vector<T> get_v(ll n){vector<T> v;for(int i=0;i!=n;i++){v.push_back(get<T>());};return v;}
template<typename T>void show_v(vector<T> v){
    for(ll i=0;i!=v.size()-1;i++) cout<<v[i]<<" ";cout<<*(v.end()-1)<<endl;}

int main() {
    string s=get<string>();
    for(ll i=0;i!=26;i++){
        if(s[i]!='a'+i){
            cout<<char('a'+i)<<"to"<<s[i]<<endl;
            break;
        }
    }

    system("pause");
}