n = int(input())
rn = int(n**0.5)+1
base = [i for i in range(n+1)]
use = [0]*(rn+1)

for i in range(2,rn+1):
    if use[i]:
        continue
    for j in range(i,rn+1,i):
        use[j] = 1
    for j in range(i**2,n+1,i**2):
        while base[j]%(i**2) == 0:
            base[j] //= i**2

ans = 0
for i in range(1,n+1):
    ans += int((n/base[i])**0.5)
print(ans)