//baoli #include <bits/stdc++.h> using namespace std; long long n,q,a[1145141]; bool f(long long e,long long d,long long x,long long y) { //cout<<((e^x)-y)*((d^x)-y)<<"\n"; return ((e^x)-y)*((d^x)-y)<=0; } int main() { freopen("function.in","r",stdin); freopen("function.out","w",stdout); cin>>n>>q; for(long long i=1;i<=n;i++) { cin>>a[i]; } while(q--) { long long x,y; bool flag=false; cin>>x>>y; for(long long i=1;i<n;i++) { //cout<<f(a[i],a[i+1],x,y)<<"\n"; if(f(a[i],a[i+1],x,y)) { cout<<i<<"\n"; flag=true; break; } } if(!flag)cout<<-1<<"\n"; } return 0; }