for _ in range(int(input())):
    n, b = list(map(int, input().split()))
    l = 0
    r = n-b
    while r-l > 1:
        m = (l+r) >> 1
        if m*(n-m) < (n-b-m)*(m+1):
            l = m
        else:
            r = m
    print(r)