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