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