from bisect import bisect_right
p = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]
acc = [1 << 61] * 100
acc[0] = 2
for i in range(1, len(p)):
    acc[i] = acc[i - 1] * p[i]
    if acc[i] > 10 ** 18:
        break
N = int(input())
print(bisect_right(acc, N))