#include<iostream>
#include<fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
int p,sol,nr2,nr5,per,sol2,q;

int main ()
{
	f>>p;
	sol=5*p;
	/*nr2=sol/2;
	nr2-=p;
	sol-=(nr2/10)*5;
	*/
	q=1;
	do
	{
		nr5=sol/5;
		nr2=sol/2;
		nr2-=nr5;
		per=nr5;
		nr2/=10;
		nr5-=nr2;
		per+=nr2;
		sol2=sol;
		sol2-=nr2*5;
		if(sol2==sol)
			q=0;
		else
			sol=sol2;
	}while(per==p && q);
	if(p==0)
		g<<1;
	else
		g<<sol;
	return 0;
}