#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,s,n) for (int i = (s); i < (n); ++i)
#define rrep(i,n,g) for (int i = (n)-1; i >= (g); --i)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define len(x) (int)(x).size()
#define dup(x,y) (((x)+(y)-1)/(y))
#define pb push_back
#define eb emplace_back
#define Field(T) vector<vector<T>>
#define pq(T) priority_queue<T,vector<T>,greater<T>>
using namespace std;
using ll = long long;
using P = pair<int,int>;

int main() {
  string s;
  cin >> s;
  string t = "abcdefghijklmnopqrstuvwxyz";
  rep(i,0,26) {
    if (s[i] != t[i]) {
      cout << t[i] << "to" << s[i] << endl;
      return 0;
    }
  }
  return 0;
}