#include <fstream>
#include <iostream>
#include <stdio.h>

using namespace std;

ifstream f("fact.in");
ofstream g("fact.out");

int main()
{

	long p,x = 0,y = 0,z;

	f >> p;


	for (long i = 1 ; i < 3000000 ; i++ ) 
	{
		z = i;

		while ( z % 2 == 0 ) 
		{
			x++;
			z = z / 2;
		}

		z = i;

		while ( z % 5 == 0 ) 
		{
			y++;
			z = z / 5;
		}


		if ((x < y) && (x == p )) 
		{
			g << i ;
			break;
		}

		if ((x > y) && (y == p )) 
		{
			g << i ;
			break;
		}

		
			

	}




	return 0;
}