Implement Queue using Linked List
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Implement a Queue using Linked List. 
A Query Q is of 2 Types
(i) 1 x   (a query of this type means  pushing 'x' into the queue)
(ii) 2     (a query of this type means to pop an element from the queue and print the poped element)

Example 1:

Input:
Q = 5
Queries = 1 2 1 3 2 1 4 2
Output: 2 3
Explanation: n the first testcase
1 2 the queue will be {2}
1 3 the queue will be {2 3}
2   poped element will be 2 the
    queue will be {3}
1 4 the queue will be {3 4}
2   poped element will be 3.

Example 2:

Input:
Q = 4
Queries = 1 2 2 2 1 3 
Output: 2 -1
Explanation: In the second testcase 
1 2 the queue will be {2}
2   poped element will be {2} then
    the queue will be empty. 
2   the queue is empty and hence -1
1 3 the queue will be {3}.

Your Task:
Complete the function push() which takes an integer as input parameter and pop() which will remove and return an element(-1 if queue is empty).

Expected Time Complexity: O(1).
Expected Auxiliary Space: O(1).

Constraints:
1 <= Q <= 100
1 <= x <= 100

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Implement Queue using Linked List

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