#include <bits/stdc++.h>
using namespace std;
void past_code();
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  bool bb = false;
  int j;
  char a = 'a', b = 'b';
  string s, t;
  cin >> s;
  for (int i = 0; i < s.length(); i++) {
    if (s[i] == a && !bb)
      bb = true;
    else if (bb) {
      if (s[i] <= b) {
        s[i] = b;
        b++;
      }
    }
    if (b == 123) break;
  }
  if (b != 123)
    cout << -1 << endl;
  else
    cout << s << endl;
  return 0;
}
