#include <iostream> 
#include <fstream> 
#include <cmath> 
using namespace std; 
int main() 
{
	ifstream f;
	ofstream g;
	f.open("factorial.in");
	int k=0, p;
	long int i;
	f >> p;
	f.close();
	g.open("factorial.out");
	for (i=1; i <= 100000000; i++)
	{
		if (i % 5 == 0)
		{
			k = k + 1;
		}
		if (k == p)
		{
			g << i;
			system("pause");
			break;
			

		}
	}
	g.close();
	return 0; 
}