#include <bits/stdc++.h>
using namespace std;
string s;
bool solve(int index, char c) {
  if (index == s.size()) {
    cout << -1;
    exit(0);
  }
  if (s[index] <= c) {
    s[index] = c;
    if (c == 'z') {
      cout << s;
      exit(0);
    }
    solve(index + 1, c + 1);
  } else {
    solve(index + 1, c);
  }
}
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> s;
  solve(0, 'a');
  return 0;
}
