//****************************************
//*?????                          **
//*?????? 1100012920              **
//*???2011.10.119                     **
//****************************************
int main()
{
	int i, k, j, count = 0, a[16];
	 while (a[0] != -1)
	{	
		count = 0;
		for (i = 0; i <= 15; i++)
		{	
		        cin >> a[i];
				if (a[i] == 0 || a[0] == -1)
			       break;
		}
		if (a[0] == -1)
			break;
		for (k = 0; k <= 15; k++)
		{
		   for (j = k + 1; j <= 16; j++)
		   {
			   if(a[j]==0)
				   break;
			   if (a[k] == 2 * a[j] || a[j] == 2 * a[k])
				   count++;
			   }
		}
	    cout << count << endl;
		
	}
	return 0;
}