#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) REP(i, 0, n)
#define REP(i, s, e) for (int i = (s); i < (int)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for (int i = (int)(s - 1); i >= (int)(e); i--)
#define all(r) r.begin(), r.end()
#define rall(r) r.rbegin(), r.rend()

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;

template <typename T, typename U>
T chmax(T& a, const U& b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template <typename T, typename U>
T chmin(T& a, const U& b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

void yes_no(bool f, string yes = "Yes", string no = "No") { cout << (f ? yes : no) << "\n"; }

void solve() {
    ll n, m;
    cin >> n >> m;
    auto jd = [&](ll x) {
        ll d = 2 * x - m;
        chmax(d, 0LL);
        ll e = (d + 3) / 4;
        return e * 2 + 4 * x <= n;
    };
    ll ok = 0, ng = 1e18;
    while (ng - ok > 1) {
        ll mid = (ok + ng) / 2;
        if (jd(mid)) ok = mid;
        else ng = mid;
    }
    cout << ok * 3 << '\n';
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int t = 1;
    cin >> t;
    rep(ti, t) solve();
    return 0;
}