#include<stdio.h>
#include<math.h>
int main()
{
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	long p,n,i,j,s,m;
	scanf("%ld",&p);
	i=0;
	j=1;
	s=0;
	if(p==0)
		printf("1");
	else
	{
		
		while(p!=0)
		{
			i=i+5;
			m=i;
			while(m%5==0)
			{
			p--;
			m=m/5;
			}
		}
	printf("%ld",i);
	}
	return 0;
}