#include<stdio.h>

int p;


int nr0(int);
void bs(int,int);

int main()
{
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	
	scanf("%d",&p);
	
	bs(1,1000000000);
	
	return 0;
}

void bs(int x,int y)
{
	if(x>=y)
	{
		if(nr0(x)==p)
		{
			if(p==0)
				printf("1");
			else
				printf("%d",x/5*5);
		}
		else
			printf("-1");
	}
	else
	{
		if(nr0((x+y)/2)<p)
			bs((x+y)/2+1,y);
		else
			bs(x,(x+y)/2);
	}
}

int nr0(int z)
{
	int s;
	
	s=-z;
	
	for(;z;z/=5)
		s+=z;
	
	return s;
}