#include<iostream>
#include<math.h>
#include<fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
int main()
{
	int n=1,p,i,c,nr=0,nr2=0,x;
	fin>>p;
	for(i=1;i<pow(10,8);i++){
		n=n*i;
		x=n;
		while(n>0){
			c=n%10;
			n=n/10;
			nr=nr+1;
		}
		while(p>0){
			c=p%10;
			p=p/10;
			nr2=nr2+1;
		}
	}
	if(nr==nr2)fout<<x;
	else fout<<-1;
	fin.close();
	fout.close();
	return 0;
}