# https://tjkendev.github.io/procon-library/python/prime/moebius-function.html
# a table of μ(n) for n in [1, N]
# O(N log log N)
def moebius_table(n):
    *p, = range(n+1)
    sq = int(n**.5)
    for x in range(2, sq+1):
        if p[x] == x:
            for y in range(x*x, n+1, x):
                p[y] = x
            for y in range(x*x, n+1, x*x):
                p[y] = 0
    res = [0]*(n+1)
    res[0] = 0; res[1] = 1
    for x in range(2, n+1):
        res[x] = (p[x] and -res[x//p[x]])
    return res

print(sum(moebius_table(int(input()))[1:]))