import sys

sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


N = I()

flag = [0]*(N+1)
ans = 0
for i in range(1,N+1):
    if flag[i]:
        continue

    count = 0
    for j in range(1,10000):
        if i*j**2 > N:
            break
        count += 1
        flag[i*j**2] = 1

    ans += count*int((N//i)**0.5)

print(ans)