const int N=1e5;

int number[N];
bool vis[N];

int main()
{
int cnt=0;
vis[0]=vis[1]=1;
for(int i=2;i<N;i)
{
if(!vis[i])
{
number[cnt]=i;
vis[i]=1;
}
for(int j=0;j<=cnt&&inumber[j]<N;j++)
{
vis[inumber[j]]=1;
if(i%number[j]==0)
break;
}
}
cout << cnt << endl;
}