#include<fstream>
using namespace std;
long long a[13]={1,6,31,156,781,3906,19531,97656,488281,2441406,12207031,61035156,305175781};
long long b[13]={5,25,125,625,3125,15625,78125,390625,1953125,9765625,48828125,244140625,1220703125};



int main(){

	long long int n=0,i,p,nr;
	ifstream f("fact.in");
	ofstream g("fact.out");
	f>>p;
	for(i=0;i<12;i++){
		if(p>a[i] && p<a[i+1]){
			nr=i;
			i=12;
		}
	}
	p=p-a[nr];
	n=b[nr];	

	while(p>0){
		n=n+5;
		p--;
		i=n;
		i=i/5;
		if(i%5==0){
			p--;
			i=i/5;
			if(i%5==0){
				p--;
				i=i/5;
				if(i%5==0){
					p--;
					i=i/5;
					if(i%5==0){
						p--;
						i=i/5;
						if(i%5==0){
						p--;
						i=i/5;
						if(i%5==0){
						p--;
						i=i/5;
						if(i%5==0){
						p--;
						i=i/5;
						if(i%5==0){
						p--;
						i=i/5;
						if(i%5==0){
						p--;
						
						}
						}
						}
						}
						}
		
					}
				}
			
			}
		
		}
		
	}
	if(p==0){
	g<<n;
	}
	else{
		g<<-1;
	}
}