#include<cstdio>
using namespace std;
int p;
int nr_zero(int x)
{
	int rez=0;
	while(x)
	{
	rez+=x/5;
	x/=5;
	}
return rez;
}
int caut_bin(int y) 
	{
	 int i,pas=1<<30;
	 for (i=0;pas;pas >>= 1) 
	  if (nr_zero(i+pas)< p) 
          i+=pas;
	return i + 1;
	}
int main()
{
	int p;
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d",&p);
	if(nr_zero(caut_bin(p))==p) 
			printf ("%d",caut_bin(p));
	else
		printf ("-1");
	return 0;
}