import std;

void main () {
    int T = readln.chomp.to!int;
    auto ans = new int[](T);
    foreach (i; 0..T) {
        int N, M; readln.read(N, M);

        bool f (int x) {
            // 充電席
            if (4L * x < N) return false;

            long rem_ch = 4L * x - N;
            return M <= rem_ch + 4L * x;
        }

        int ok = 10 ^^ 9, ng = 0;
        while (1 < abs(ok - ng)) {
            int mid = (ok + ng) / 2;
            if (f(mid)) {
                ok = mid;
            }
            else {
                ng = mid;
            }
        }

        ans[i] = ok;
    }

    foreach (a; ans) writeln(a);
}

void read (T...) (string S, ref T args) {
    import std.conv : to;
    import std.array : split;
    auto buf = S.split;
    foreach (i, ref arg; args) {
        arg = buf[i].to!(typeof(arg));
    }
}