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