def zmien(s1:Stream[Int],s2:Stream[Int],mark:String):Stream[Int]=
    {
       val p1#::xs1 =s1
       val p2#::xs2=s2

//    (s1,s2) match {
  //       case (Stream.Empty,Stream.Empty) => println("dupaaaa")
    //   }

       mark match {
         case "+" => if (xs1==Stream.Empty) p2#::zmien(s1,xs2,"+")
                        else if (xs2==Stream.Empty) p1#::zmien(xs1,s2,"+")
                     else (p1+p2)#::zmien(xs1,xs2,"+")
         case "-" => (p1-p2)#::zmien(xs1,xs2,"-")
         case "*" => (p1*p2)#::zmien(xs1,xs2,"*")
         case "/" => (p1/p2)#::zmien(xs1,xs2,"/")
       }

      }
    val l1 = Stream.cons(5,Stream.cons(7,Stream.cons(4,Stream.cons(10,Stream.empty))))
    val l2 = Stream.cons(1,Stream.cons(2,Stream.cons(3,Stream.empty)))

    val l3 = zmien(l1,l2,"+")
 //   println(zmien(l1,l2,"+"))

  l3.take(4).toList