#include <bits/stdc++.h>
using namespace std;
const int INF = (int)1e9;
const int mod = (int)1e9 + 7;
const int MAXN = (int)3e5 + 5;
void solve() {
  string s;
  cin >> s;
  char ch = 'a';
  for (int i = 0; i < s.length(); i++) {
    if (ch == 'a') {
      if (s[i] == 'a') ch++;
    } else {
      if (s[i] <= ch) {
        s[i] = ch;
        ch++;
      }
    }
    if (ch > 'z') break;
  }
  if (ch > 'z')
    cout << s << "\n";
  else
    cout << -1 << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  int t = 1;
  while (t--) {
    solve();
  }
}
