终于对了！！
var
  a:array[1..16] of integer;
  i,n,j,x,sum:integer;
begin
  read(a[1]);
  while a[1]<>-1 do begin
    n:=2;sum:=0;
    repeat
      read(a[n]);
      inc(n);
    until a[n-1]=0;
    dec(n);
    for i:=1 to n do
      for j:=1 to n do if a[j]=2*a[i] then inc(sum);
    writeln(sum);
    read(a[1]);
  end;
end.