#include <iostream>
#include <fstream>

using namespace std;

unsigned long long factorial(unsigned long long p) {
	long x=1,zero=0;
	for (unsigned long long i=2 ; i<1000000000 ; i++) {
		x=x*i;
		while (x%10==0 && x/10!=0) {
			zero++;
			x=x/10;
		}
		x=x%10;
		if (zero==p) return i;
		else if (zero>p) return -1;
	}
	//return zero;
}

int main() {
	ifstream f("fact.in");
	ofstream g("fact.out");
	unsigned long long p; //n=1,zero=0;
	f>>p;
	f.close();
	//while (zero<p) {
	//	n++;
	//	zero=factorial(n);
	//}
	//if (zero>p) g<<"-1";
	//else g<<n;
	g<<factorial(p);
	g.close();
	return 0;
}