n = int(input())
if n == 1:
    print(0)
    exit()
d = [0] + [(n // i) ** 2 for i in range(1, n + 1)]
for i in range(n, 0, -1):
    for j in range(2 * i, n + 1, i):
        d[i] -= d[j]
ans = (sum(d[2:]) - (n - 2)) // 2
for x in range(2, n + 1):
    ans -= n // x - 1
print(ans)