TLE漫天飞！！！

#include <bits/stdc++.h>
using namespace std ;
int main (  )
{
	int a,ans=1,sum=1;
	cin >> a;
	bool f;
	if (a==1)
	{
		sum=2;
	}
	while (ans<a)
	{
		sum+=2;
		f=true;
		for (int i=3;i*i<=sum;i+=2)
		{
			if (sum%i==0)
			{
				f=false;
				break;
			}
		}
		if (f=false)
		{
			ans++;
		}
	}
	cout << sum;
	return 0 ;
}