int a[15];
int main()
{
	int num, doub;
	char b;
	int comp_with_zero;
	for (; 1;)
	{
		num = 0;
		doub = 0;
		comp_with_zero = 1;
		b = 'a';
		for (int ai = 0; ai < 15; ai++)
		{
			a[ai] = 0;
		}
		for (; 1;)
		{
			b = cin.get();
			if ((b == '0') && (a[num] == 0))
			{
				break;
			}
			if ((b - '0' < 10) && (b - '0' >= 0))
			{
				a[num] *= 10;
				a[num] += (b - '0');
			}
			else
			{
				if (b == ' ')
				{
					a[num] *= comp_with_zero;
					num += 1;
					comp_with_zero = 1;
				}
				if (b == '-')
				{
					comp_with_zero = -1;
				}	
			}
		}
		for (int i = 0; i <= num; i++)
		{
			for (int ii = i; ii <= num; ii++)
			{
				if (a[i] == 0)
					break;
				if ((a[i] % 2 == 0) && (a[i] / 2 == a[ii]))
					{
						doub += 1;
					}
				if ((a[ii] % 2 == 0) && (a[ii] / 2 == a[i]))
				{
					doub += 1;
				}
			}
		}
		cout << doub << endl;
	}
	return 0;
}
