#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);
  string s,t,u="abcdefghijklmnopqrstuvwxyz";cin>>s;
  rep(i,s.size()){
    if(s[i]!=u[i]){
      t+=u[i];
      t+=s[i];
      break;
    }
  }
  cout<<t[0]<<"to"<<t[1]<<endl;
}