n=int(input())
if n==1:
    print(0)
    exit()
elif n==2:
    print(1)
    exit()
ele=[]
for i in range(3,n+1,2):
    for e in ele:
        if i%e==0:
            break
        if e**2>i:
            ele.append(i)
            break
    else:
        ele.append(i)
sel=set(ele)
cnt=0
for r in ele:
    p=r**2-2
    if p in sel:
        cnt+=1
    if p>n:
        break
print(cnt*2+1)