#include <bits/stdc++.h>
using namespace std;
const double EPS = (double)1e-9;
const double PI = (double)acos(-1.0);
int irand(int lo, int hi) {
  return (((double)rand()) / (RAND_MAX + 1.0)) * (hi - lo + 1) + lo;
}
string toString(long long x) {
  stringstream ss;
  ss << x;
  return ss.str();
}
long long toNumber(string S) {
  long long ret;
  sscanf(S.c_str(), "%lld", &ret);
  return ret;
}
const int INF = (int)2e9;
const long long MOD = (long long)1e9 + 7;
char s[100005];
int main() {
  scanf("%s", s);
  int n = strlen(s);
  char temp = 'z';
  for (int i = n - 1; i >= 0; i--) {
    s[i] = max(s[i], temp);
    if (s[i] == temp) temp--;
  }
  if (temp + 1 == 'a') puts(s);
  if (temp + 1 != 'a') puts("-1");
  return 0;
}
