#include <bits/stdc++.h>
using namespace std;
mt19937 mr((unsigned long long)time(0));
char in[10][10] = {"1.in", "2.in", "3.in", "4.in", "5.in",
                   "6.in", "7.in", "8.in", "9.in", "10.in"};
char out[10][10] = {"1.out", "2.out", "3.out", "4.out", "5.out",
                    "6.out", "7.out", "8.out", "9.out", "10.out"};
char a[1000005];
int ok(int x) {}
void solve() {
  scanf("%s", a);
  int len = strlen(a);
  char c = 'a';
  for (int i = 0; i < len && c <= 'z'; i++) {
    if (a[i] <= c) {
      a[i] = c;
      c++;
    }
  }
  if (c <= 'z')
    printf("-1");
  else
    printf("%s", a);
}
int main() { solve(); }
