#include <bits/stdc++.h>
using namespace std;
const long long N = 2e5 + 36;
const long long M = 2e2 + 36;
const long long INF = 2e9 + 7;
const long long MOD = 987654323;
const long long MOD1 = 1e9 + 7;
const long long MOD2 = 1e9 + 9;
const int XK[4] = {-1, 0, 1, 0};
const int YK[4] = {0, -1, 0, 1};
const int X[8] = {1, 1, -1, -1, 2, 2, -2, -2};
const int Y[8] = {2, -2, 2, -2, 1, -1, 1, -1};
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  string s;
  cin >> s;
  int now = 'a';
  for (int i(0); i < (int)s.size(); ++i) {
    if (int(s[i]) <= now) {
      s[i] = char(now);
      now++;
      if (now == int('z') + 1) break;
    }
  }
  if (now == int('z') + 1) {
    cout << s << endl;
  } else {
    cout << -1 << endl;
  }
  return 0;
}
