N,P = map(int, input().split())

if P > 1:
    L = [0]*(N+1)
    n = 2
    num = P
    while n <= P**0.5:
        if P%n == 0:
            num = n
            break
        n += 1
    if num*2 <= N:
        ans = N//2-1
        for i in range(N//2+1, N+1):
            n = 2
            while n <= i**0.5:
                if i%n == 0:
                    ans += 1
                    break
                n += 1
    else:
        ans = 1

print(ans)