#include<iostream> #include<vector> #include<algorithm> using namespace std; using ll = long long; int main(){ cin.tie(nullptr); ios::sync_with_stdio(false); int n; cin>>n; vector<ll> a(n); for(int i = 0;i<n;i++){ cin>>a[i]; } vector<ll> now,use; for(int i = 0;i<n;i++){ ll all = 0; ll aa = a[i]; all |= 1ll << i; for(int i = 0;i<now.size();i++){ ll e = now[i]; ll nxt = e ^ aa; if(nxt<aa){ aa = nxt; all ^= use[i]; } } if(aa!=0){ now.push_back(aa); use.push_back(all); continue; } vector<int> ans; for(int j = 0;j<63;j++){ if(all>>j&1) ans.push_back(j+1); } cout<<ans.size()<<endl; for(int j = 0;j<ans.size();j++){ if(j) cout<<" "; cout<<ans[j]; } cout<<endl; return 0; } cout<<-1<<endl; }