#include<iostream>
using namespace std;



int main() {
	long int  Num = 0;
	long int pNum = 0;
	bool prim = true;
	long int x = 1;
	long int y = -1;
	while(6*x+y < 600851475143)
	{
		Num = 6*x+y;
		if(y == 1)
			x+=1;
		y*=-1;
		long int x2 = 1, y2 = -1;
		long int  Num2 = 0;
		bool pCheck = false;
		while(6*x2+y2<Num)
		{
			Num2 = 6*x2+y2;
			if(y2 == 1)
				x2+=1;
			y2*=-1;
			if(Num%Num2 == 0)
				pCheck = true;
		}
	}
	cout << pNum << "\n";
	system("Pause");
    return 0;
}