n, t = map(int, input().split())
if n == 1: exit(print("NaN"))
l = 1
r = 10 ** 7
while r - l > 1:
    m = (l + r) >> 1
    l0 = 0
    r0 = 10 ** 20
    while r0 - l0 > 1:
        k0 = (l0 + r0) >> 1
        if m * m > k0 * k0 * n:
            l0 = k0
        else:
            r0 = k0
    k = l0
    cnt = m - 1 - k
    if cnt < t:
        l = m
    else:
        r = m
print(r-1)