import sys
input = sys.stdin.readline
from collections import Counter

N=int(input())

X=[i for i in range(N+1)]

for i in range(1,N+1):
    if X[i]!=i:
        continue

    for j in range(1,N+1):
        if i*j*j<=N:
            X[i*j*j]=i
        else:
            break

C=Counter(X)
ANS=0

for c in C:
    ANS+=C[c]*C[c]

print(ANS-1)