int main()
{         
	int	A[16],pause,i,k,m,count;

	for(;;){
		    count=0;
		    for (i=0;i<16;i++){
		               scanf("%d",&A[i]);
		               if(A[i] == 0 ||A[i] == -1){
                       break;
                       }
	        }
			if(A[i] == -1){
						break;
			}
			for(i=0;i<16;i++){
							if(A[i] == 0){
								pause=i;
								 break;
							}
      			}
			for(k=1;k<pause;k++){
					for(i=0;i<pause-k;i++){
							if (A[i] <= A[i+1])/*????*/
								{
									m=A[i];
									A[i]=A[i+1];
									A[i+1]=m;
								}
					}
			}
			for(k=0;k<pause;k++){
					for(i=k+1;i<pause;i++){
							if ( A[k] == 2*A[i])/*??2?*/{
								count++;
							}
					}
			}	
			printf("%d\n",count);
	}     
   return 0;
}