#include<fstream.h>
ifstream intrare("fact.in");
ofstream iesire("fact.out");
long p,n;
int cinci(long k)
{
	int count=1;
	long act=25;
	while(k%act==0)
	{
		act=act*5;
		count++;
	}
	return count;
}

int main()
{
	intrare>>p;
	if(p==0)iesire<<"1";
	else
	{
		long act=5,nr=1;
		while(nr<p)
		{
			act+=5;
			nr+=cinci(act);
		}
		if(nr==p)iesire<<act;
		else iesire<<"-1";
	}
	return 0;

}