#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define all(x) (x).begin(),(x).end()
const int mod=1000000007,MAX=100005,INF=1<<30;

int main(){
    
    //std::ifstream in("text.txt");
    //std::cin.rdbuf(in.rdbuf());
    
    string S;cin>>S;
    sort(all(S));
    reverse(all(S));
    bool ok=true;
    
    for(int i=S.size()-1;i>=1;i--){
        if(S[i]!=S[i-1]&&(i>=2||S[i]!=0)){
            ok=false;
            swap(S[i],S[i-1]);
            break;
        }
    }
    
    if(ok) cout<<-1<<endl;
    else cout<<S<<endl;
}