#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)

using namespace std;
using ll = long long;

void solve() {
    int n, m;
    cin >> n >> m;
    
    int ac = 0, wa = n/4+1;
    while (abs(ac-wa) > 1) {
        int wj = (ac+wa)/2;
        
        auto ok = [&]{
            int need = 2*wj-m;
            int y = 0;
            if (need > 0) y = (need+3)/4;
            return 2*y+4*wj <= n;
        }();
        
        (ok ? ac : wa) = wj;
    }
    
    cout << ac*3 << '\n';
}

int main() {
    cin.tie(nullptr) -> sync_with_stdio(false);
    
    int t;
    cin >> t;
    
    while (t--) solve();
    
    return 0;
}