Olympiad

total = int(input())
first = int(input())

if not total:
    print(0)
elif total <= first:
    print(1)
else:
    l = 1
    r = total + 1

    while r - l > 1:
        mid = l + (r - l) // 2
        summ = 0.5 * mid * (mid - 1) + mid * first
        if summ < total:
            l = mid
        else:
            r = mid
    print(r)