#include<bits/stdc++.h> using namespace std; bool cmp(char a,char b){ return a>b; } int main(){ string s; cin>>s; int n=s.size(); int i=n-1,j; int k=0; while(1){ i--; if(i<0)break; j=n-1; while(j!=i&&s[i]<=s[j]){ j--; } if(i!=j){ k=1; swap(s[i],s[j]); break; } } if(k){ sort(s.begin()+i+1,s.end(),cmp); cout<<s; }else{ cout<<-1; } return 0; }