#include <bits/stdc++.h>

using namespace std;

bool t [ 30005 ] = { 0 } ;

int main() {

	t [ 0 ] = 1 ;

	for ( int i = 2 ; i <= 10000 ; i ++ ) {

		for ( int j = 2 ; i * j <= 10000 ; j ++ ) {

			t [ i * j ] = 1 ;
		}
	}

	int n, z = 0 ;
	cin >> n ;

	for ( int i = 1 ;  ; i ++ ) {

		if ( t [ i ] == 0 ) {
			z ++ ;
		}

		if ( z - 1 == n ) {
			cout << i ;
			return 0 ;
		}
	}

}

麻烦各位高人指点一下，谢谢啦