def MillerRabin_64bit(x):
    if x <= 1:
        return False
    if x == 2:
        return True
    if x % 2 == 0:
        return False
    if x < 1 << 30:
        test = [2, 7, 61]
    else:
        test = [2,325,9375,28178,450775,9780504,1795265022]
    s = 0
    d = x - 1
    while d & 1 == 0:
        s += 1
        d >>= 1
    for i in test:
        if x <= i:
            return True
        y = pow(i,d,x)
        if y == 1 or y == x - 1:
            continue
        c = 0
        for j in range(s-1):
            y = y * y % x
            if y == x - 1:
                c = 1
                break
        if not c:
            return False
    return True
n = int(input())
x = 2
ans = 1
for i in range(3,10000):
    if x > n:
        print(ans-1)
        break
    if MillerRabin_64bit(i) == False:
        continue
    ans += 1
    x *= i