#include <cstdio>
int x,n,nr,i,max,min,mij;
bool verif (int y){
	int p;
	p=0;
	while (y>=5){
		p=p+y/5;
		y=y/5;
	}
	if (p<n) return true;
	return false;
}
int main(){
	freopen ("fact.in","r",stdin);
	freopen ("fact.out","w",stdout);
	scanf ("%d",&n);
	x=2; nr=1;
/*	while (nr<27){ x=x*2; nr++;} 
	for (i=0;x!=0;x=x/2)
		if (verif(i+x)) i=i+x;*/
	min=1; max=100;
	while (min<max){
		mij=(min+max)/2;
		if (verif(mij)) min=mij+1;
		else max=mij;
	}
	if (n==0) printf ("0");
    else { x=min; nr=0;
	       while (min>=5){ nr=nr+min/5; min=min/5;}
		   if (nr==n) printf ("%d",x);
		   else printf ("-1");}
	return 0;
}