#include <iostream> 
#include <stdio.h>
#include <math.h>
using namespace std ;





int main(){
	
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	int n;
	cin >> n ;
	
	if (n < 0) {
		cout << -1 << endl;
	}
	else if (n == 0){		
		cout << 1 << endl;
	}
	else {
		int p = 0 , nr = 0 , l ,k;
		while (nr < n){
			p += 5;
			nr++;
			l = p ;
			k = -1;
			while (l % 5 == 0 ){
				k++;
				l/=5;
			}
			nr+=k;
		}
		if (nr == n) cout << p << endl;
		else		 cout << -1 << endl;
	}
	return 0 ;
}