/*
 *  qizhongceshi9.cpp
 *  ???????????????????????????????
 *  Created on: 2010-11-13
 *      Author: william
 */
int main()  //???
{
	int a[16], k, i, j;  //??????k i j ???a[]
	for(k=0;;k++)  //for?? 
	{
		int n=-1, num=0;  //?????? n num ????
		for(i=0;i<16;i++)  //for?? ???a??
		{
			cin>>a[i];
			n++;         //????? n?1
			if(a[i]==0)  //??????????0  
				break;  //?????
		}
		if(a[0]==-1) //??????????-1 ?????
			break;
		for(i=0;i<n;i++)  //for??
			for(j=i+1;j<n;j++)  //for??
			{
				if(a[i]==2*a[j]||a[j]==2*a[i])  //???????? ??2???
					num++;  //num??
			}
		cout<<num<<endl;  //??num
	}
	return 0; //??
}  //??