def solve():
    N, B = [int(s) for s in input().split()]

    ok, ng = 0, N + 1
    while abs(ok - ng) > 1:
        mid = (ok + ng) // 2

        if (N - B - mid + 1) * mid > (N - mid + 1) * (mid - 1):
            ok = mid
        else:
            ng = mid

    print(ok)


if __name__ == "__main__":
    T = int(input())

    for _ in range(T):
        solve()