#include<fstream>
using namespace std;
ifstream cin("fact.in");
ofstream cout("fact.out");
struct fact{
	int zer;
	int num;
};
int p,o=1;
bool u=true;
fact a[100000000];
int main(){
	cin>>p;
	a[0].num=5;
	a[0].zer=1;
	while(u){
		a[o].num=a[o-1].num+5;
		int x=a[o].num;
		int k=1;
		if((x/5)%5==0){
			x=x/5;
			while(x!=0){
					x=x/5;
				    k++;
			}
			k--;	
		}
		a[o].zer=k+a[o-1].zer;
		if(a[o].zer>p)u=false;
		o++;
	}
/*	int st=0,dr=o,pv;
	while(st<dr){
		pv=st+dr;
		pv/=2;
		if(a[pv].zer<a[p].zer)st=pv+1;
		else dr=pv-1;	
	}
	pv=st+dr;
	pv/=2;
	if(a[pv].zer<pv)pv++;
	if(a[pv].zer==p)cout<<a[pv].num;
	else cout<<"-1";*/
	if(p==a[o-2].zer)cout<<a[o-2].num;
	else cout<<"-1";
	return 0;
}