#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define endl "\n"
#define rep(i, a, n) for (int i = a; i < n; ++i)
#define all(x) (x).begin(), (x).end()

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    string s;
    cin >> s;

    rep(i, 0, 26) {
        if (s[i] != 'a' + i) {
            cout << char('a' + i) << "to" << s[i] << endl;
            break;
        }
    }
    return 0;
}