#include <fstream>
using namespace std;

ifstream f("ciur.in");
ofstream g("ciur.out");

bool x[2000005];
long long n, k;

int main()
{
    bool x[2000005];
    long long k, n;
    in >> k;
    for (long long i=2; i<=n;i++)
        if (!=x[i])
    {
        n++;
        for (long long j = i*i; j<=n; j+=i)
            x[j]=true;
    }
    out<< k;
}