#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll=long long;
using ld=long double;
using st=string;
using P=pair<ll,ll>;
typedef atcoder::modint mint;
ll inf=9e18;
template<class... T>
constexpr auto max(T... a){return max(initializer_list<common_type_t<T...>>{a...});}
template<class... T>
constexpr auto min(T... a){return min(initializer_list<common_type_t<T...>>{a...});}
template<typename T, int s, int i = 0>
auto vec(const ll (&sizes)[s], const T& init = T()){
  if constexpr(i < s) return vector(sizes[i], vec<T, s, i+1>(sizes, init));
  else return init;
}


int main(){
  ll t,l,r;
  cin>>t;
  for(ll T=0;T<t;T++){
    cin>>l>>r;
    ll b=1;
    while(r>=b){
      b<<=1;
    }
    b>>=1;
    if(l<b){
      cout<<b*(b-1)<<"\n";
    }else{
      cout<<-1<<"\n";
    }
  }
}