import math
ans=0
M=998244353
n=int(input())
D=[0]+[1]*n
P=[0]+[1]*n
for i in range(2,n+1):
    if P[i]:
        for j in range(i,n+1,i):
            P[j]=0
            if j%(i**2)==0:
                D[j]=0
            else:
                D[j]*=-1
print(sum(D))