seive prime

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int i,j,k,l,m,n=500001;
    bitset<10000007>bs;
    //vector<in >v(n,false);

    vector<long long > x;
    vector<long long > :: iterator xi;
   bs.set();
   bs[0]=bs[1]=0;
   x.push_back(2);
    for(i=3;i*i<n;i+=2)
    {
        if(bs[i])
        {
            for(j = i*i ;j<n ;j+=i)
            {
                bs[j]=0;
                x.push_back(i);

            }
        }

    }
   cin>> m;
cout<<x[m-1]<<endl;


}