#include <bits/stdc++.h>
using namespace std;
string s;
int main() {
  ios::sync_with_stdio(false);
  cin >> s;
  char now = 'a';
  for (int i = 0; i < s.length(); i++) {
    if (s[i] <= now) s[i] = now, now++;
    if (now > 'z') break;
  }
  if (now > 'z')
    cout << s;
  else
    cout << -1;
}
