from collections import deque

def primes(n):
    p = []
    flgs = [False]*(n+1)
    
    for i in range(2, n+1):
        if not flgs[i]:
            p.append(i)
            for j in range(i*2, n+1, i):
                flgs[j] = True
    return p

N = int(input())
answer = 0
ps = primes(N)

queue = deque([(p, i, 0) for i, p in enumerate(ps)])

while queue:
    now, end, count = queue.popleft()
    
    cnt = N//now
    
    if count%2 == 0:
        answer += cnt*(cnt-1) // 2
    else:
        answer -= cnt*(cnt-1) // 2
        
    for j, p in enumerate(ps[end+1:], start=end+1):
        if now*p > N: break
        queue.append((now*p, j, count+1))

for i in range(2, N+1):
    if N//i == 1: break
    answer -= (N//i)-1

print(answer)