#include <stdio.h>


int nr5(int nr)
{
	int j = 0;
	while (nr % 5 ==0)
	{
		nr = nr / 5;
		j++;
	}
	return j;
}

int main()
{
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	int n,i,c = 0;
	scanf("%d",&n);
	for (i = 5;c<n;i+=5)
	{
		c +=nr5(i);
	}
	if (n == 0)
	{
		printf("1");
	}
	else
	if (c == n)
	{
		printf("%d", i-5);
	}
	else
	{
		printf("-1");
	}
	return 0;
}