from collections import Counter,defaultdict,deque
from heapq import heappop,heappush,heapify
from bisect import bisect_left,bisect_right 
import sys,math,itertools,pprint,fractions
mod = 998244353
INF = float('inf')
def inp(): return int(sys.stdin.readline())
def inpl(): return list(map(int, sys.stdin.readline().split()))
def inpl_1(): return list(map(lambda x:int(x)-1, sys.stdin.readline().split()))
def err(x): print(x); exit()

n = inp()
res = 0
a = [set() for _ in range(n+1)]
seen = [0]*(n+1)
for i in range(2,n+1):
    if seen[i]:
        continue
    for j in range(i,n+1,i):
        seen[j] = 1
        k = j
        while k%i == 0:
            if i in a[j]:
                a[j].discard(i)
            else:
                a[j].add(i)
            k //= i
sq = [i*i for i in range(1,n+1)]

for i in range(1,n+1):
    j = 1
    for key in list(a[i]):
        j *= key
    ok = 0
    ng = n
    while abs(ok-ng) > 1:
        mid = (ok+ng)//2
        if sq[mid]*j <= n:
            ok = mid
        else:
            ng = mid
    # print(i,ok)
    res += ok+1

    
print(res)