#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
int main()
{
int n; cin>>n;
vector<pii> a;
int s=0;
for(int i=0; i<n; i++){
int v; cin>>v; s+=v;
a.push_back(make_pair(v, i+1));
}
sort(a.begin(), a.end());
if(a[0].first!=(s-a[0].first) && n!=1){
cout<<"1"<<endl<<a[0].second<<endl;
}
else{
cout<<"-1"<<endl;
}
}
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