#include <stdio.h>

int main ()
{
	freopen("fact.in", "r", stdin);
	freopen("fact.out", "w", stdout);
	int p, i=5, x=0, y;;
	scanf("%d", &p);
	if (p!=0) {
		while (p!=0) {
			y=i;
			x=0;
			while (y%5==0) {
				x++;
				y/=5;
			}
			p-=x;
			if (p<=0) {
				break;
			}
			i+=5;
		}
		printf("%d", i);
	} else {
		printf("1");
	}
	return 0;
}