#include<cstdio>
using namespace std;
int main()
{FILE*f=fopen("fact.in","r");            
FILE*g=fopen("fact.out","w");
int p,poz,p1,k,x,i,j=1,rez,rez1,rez2;
fscanf(f,"%d",&p);
if(p==0)
	fprintf(g,"1");
if(p>=1 && p<5)
	fprintf(g,"%d",p);
if(p==5)
	fprintf(g,"-1");
if(p>=6){
	poz=5;
	p1=5;
	k=0;
	x=6;
	while(x<p){
		poz=poz+5;
		i=poz;
		k=0;
		while(i%5==0){
			k++;
			i=i/5;
		}
		x=x+5+k;
	}
	if(x>p){
		x=x-5-k;
		poz=poz-5;
		while(x<p){
			x++;
			poz++;
		}
		
	}
	rez=poz*5;
	fprintf(g,"%d",rez);
}
}