FOURTH ASSIGNMENT
1) You have given a Python list. Write a program to find value 20 in the list, and if it is present, replace it with 200. Only update the first occurrence of an item.
SOL:
	 l = [5,10,15,20,25,50,20]
	 for i in range(len(l)):
  	  if(l[i]==20):
  	      l[i] = 200
  	      break
	 print(l)


2)Given a Python list, write a program to remove all 
occurrences of item 20.

Given input : list1 = [5, 20, 15, 20, 25, 50, 20]

Expected output:[5, 15, 25, 50]

SOL:

	 l = [5,20,15,20,25,50,20]
	ans = []
	for i in l:
 	   if(i != 20 ):
  	      ans.append(i)
	print(ans)


3)Given a two Python list. Write a program to iterate both lists simultaneously and display items from list1 in original order and items from list2 in reverse order.

Given input : 
list1 = [10, 20, 30, 40]
list2 = [100, 200, 300, 400]

Expected output:
10 400
20 300
30 200
40 100

SOL:

 	list1 = [10,20,30,40]
	list2 = [100,200,300,400]
	for i in range(4):
  	  print(list1[i],list2[4-i-1])