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