#include<fstream>
using namespace std;

int main()
{
	int p,n=1,c5=0,cpy;
	ifstream In("fact.in");
	In>>p;
	In.close();
	if(p)
	{
		while(c5<p)
		{
			n++;
			if(n%5==0)
			{
				cpy=n;
				while(cpy)
				{
					if(cpy%5==0) c5++;
					cpy/=5;
				}
			}
		}
		if(n%p) n=-1; 
	}
	
	ofstream Out("fact.out");
	Out<<n;
	Out.close();
	return 0;
}