n = int(input())

num = 0
x = 1

for i in range(1,n+1):
    sq = (~i)**2
    if sq > n:
        break
    else:
        x += 1
        for j in range(i+1,n+1):
            if j*sq <= n:
                num += 1

print(2*num + n + x*(x-1))