#include <fstream>
using namespace std;
ifstream fin("factorial.in");
ofstream fout("factorial.out");
int n,s,p,ciur[100001],i,j,x;
int main()
{fin>>n;
 for(i=2;i<=n;i++)
  if(ciur[i]==0)
   {for(j=i+i;j<=n;j+=i)
     ciur[j]=1;
   }
 p=2;x=2;
 while(x<=n)
  {while(p<=n)
    {s=s+n/p;
     p*=x;
    }
   p=x+1;
   while(ciur[p]==1) p++;
   x=p;
  }
 fout<<s<<'\n';
 fin.close();
 fout.close();
 return 0;
}