n = int(input())

p = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59]

t = 1
i = 0
ans = []
while True:
    if t * p[i] <= n:
        t *= p[i]
        ans.append(p[i])
        i += 1
    else:
        break
    
print(len(ans))