#include <bits/stdc++.h>
using namespace std;
int main() {
  char s[100010];
  char c = 'a';
  cin >> s;
  for (int i = 0; s[i] != 0; i++) {
    if (s[i] <= c && c <= 'z') s[i] = c, c++;
  }
  if (c == 'z' + 1)
    cout << s;
  else
    cout << -1;
  return 0;
}
