Skew Heap:

show your tree clearly

Given four sets with priorities S1{10, 15, 3, 8, 20, 5, 17, 15, 19, 12, 7, 113, s,-{18, 2, 16, 5, 9, 7, 12, 8, 16, 9), s,-(10, 15, 3, 8, 20, 5), and S4 (16, 15, 9, 17, 12, 2, 6}