fix and Empty method
Pairing heap and presorted array heap

Presorted Array heap - my "knowhow"
It is ternary unbalanced tree with presorting of node's children.

Algo (min heap):
A, B, C ... - trees
vA, vB, vC - value of tree root
Insertion (A - heap's tree):
- creation selfstanding tree B
- if main heap is empty, then heap B
- if vB < vA, then put A as a child of B, and B becomes a heap
- otherwise put B as a child of A
Putting tree (A) as a child of other (B):
- if B has less then 3 children, then simply add A to a children of B
- otherwise
-- sort children of B so that vC1 < vC2 < vC3
-- put C3 as a child of C2
-- put C2 as a child of C1
-- put A as a child of B
Popping root (A):
- if A has no children, then heap is empty
- if A has 1 child B, then heap is B
- if A has 2 children, then
-- sort them so that vC1 < vC2
-- put C2 as a child of C1
-- heap is C1
- if A has 3 childre, then
-- sort them so that vC1 < vC2 < vC2
-- put C3 as a child of C2
-- put C2 as a child of C1
-- heap is C1