n=int(input())
p=[[] for i in range(n+1)]
for i in range(2,n+1):
  if len(p[i])==0:
    for j in range(i,n+1,i):
      p[j]+=[i]
a=0
for i in range(2,n+1):
  c=0
  for k in range(1,1<<len(p[i])):
    x=1
    for j in range(len(p[i])):
      if (k>>j)&1:
        x*=p[i][j]
    c+=(n//x-i//x)*((-1)**(k.bit_count()%2+1))
  a+=c-(n//i-i//i)
print(a)