def isqrt(n):
    assert n >= 0
    if n < 2: return n
    x = int(n**0.5)*2
    while x*x > n:
        x = (x+n//x)//2
    return x

n = int(input())
ans = 0
r = [1]*(n+1)
for i in range(1,n+1):
    if r[i] == 0: continue
    c = 0
    for j in range(1,n+1):
        v = i*j*j
        if v > n: break
        c += 1
        r[v] = 0
    ans += isqrt(n//i)*c
print(ans)