#include<iostream>
#include<fstream>
using namespace std;
ifstream f("ciur.in", ios::in);
ofstream g("ciur.out", ios::out);
int main()
{
    int n,k,i,a[30],p;
    f>>n;
    for(i=1;i<=n;i++)
    a[i]=i;
    p=2;
    k=0;
    while(n!=0)
    {
               for(i=1;i<=n;i++)
    {
                     if(a[i]%p==0)
                     a[i]=a[i+1];
                     n--;}
    p++;
    k++;}
    g<<k;
    return 0;}