n = int(input())
base = [1]*(n+1)
use = [0]*(n+1)
ans = 1
for i in range(2,n+1):
    if use[i]:
        ans += base[i]*2-1
        continue
    for j in range(i,n+1,i):
        use[j] = 1
        c = 0
        now = j
        while now % i == 0:
            now //= i
            c += 1
        base[j] *= (c//2)+1
    ans += base[i]*2-1
print(ans)