#include <bits/stdc++.h>
using namespace std;

#define loop(i,b,e) for(auto i=b;i<=e;i++)
#define reloop(i,e,b) for(auto i=e;i>=b;i--)
#define all(x) x.begin(),x.end()
#define ll long long
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define pf printf
#define sf scanf

string alph={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};

bool CanU(string s) {
   int j=0;
   loop(i,0,25) {
      if(s[i] > alph[j])
         return false;
      else j++;
   }
   return true;
}

string tmp,s,a="abcdefghijklmnopqrstuvwxyz";
int b;


int main(){
   cin >> s;
   if(s.length() < 26) pf("-1");
   else {
      loop(i,0,s.length()-26) {
         tmp = s.substr(i,26);
         if(CanU(tmp)) {
            s.replace(i,26,a);
            cout << a;
            return 0;
         }
      }
      pf("-1");
   }
}