#include "richest.h"
#include<bits/stdc++.h>
using namespace std;
#define vi vector<int>
#define pi pair<int,int> 
#define vp vector<pi> 
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define pb push_back
namespace solution {
    int N,T,S;
    const int MAXN=1e6+50;
    vi V;//node_set
    namespace Query {
        bool ban[MAXN];
        vi qry(vp e) {
            vi result;
            for(int u:V) ban[u]=false;
            vi a,b;
            for(auto i:e) a.pb(i.first),b.pb(i.second);
            vi c=ask(a,b);
            for(int i=0;i<e.size();++i) {
                ban[a[i]^b[i]^c[i]]=true;
            }
            for(int u:V) if(!ban[u]) result.pb(u);
            return result;
        }
    };using Query::qry;
    
    namespace sub1 {
        int sol() {
            vp e;rep(i,0,N-1) rep(j,0,i-1) e.pb({i,j});
            vi ans=qry(e);
            assert(ans.size()==1);
            return ans.back();
        }
        bool check() {return N==1000;}
    } 
    int solve() {
        V.resize(N);rep(i,0,N-1) V[i]=i;
        if(sub1::check()) return sub1::sol();
        return -1;//failed
    }
};
#undef rep
#undef vi
#undef pi
#undef vp
#undef pb 
int richest(int N, int T, int S) {
    solution::N=N,solution::T=T,solution::S=S;
    return solution::solve() ;
}