#include <bits/stdc++.h>
using namespace std;
const int inf = 2e9;
const int N = 1e5 + 5;
const int md = 1e9 + 7;
long long dp[N][26], n, x;
string s;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> s;
  x = 0;
  for (int i = 0; i < s.size(); ++i) {
    if (s[i] - 'a' <= x) {
      s[i] = x + 'a';
      x++;
      if (x == 26) break;
    }
  }
  if (x != 26)
    cout << -1;
  else
    cout << s;
}
