#include<stdio.h>
#include<math.h>
long int nr_zerouri(long int x)
{
	long int aux=x,suma=0;
	while(x!=0)
	{
		suma+=x%5;
		x=x/5;
	}
	return (aux-suma)/4;
}
int main()
{
	long int i,cerinta,P;
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d",&P);
	if(P==0)
		printf("1");
	else
	{
	cerinta=P;
	P=4*P;
	while(P%5!=0)
		P++;
	i=P;
	for(i=P;i;i+=5)
		if(nr_zerouri(i)==cerinta)
		{printf("%d",i);break;}
	}
	return 0;
}