Suppose we have some input data describing a graph of relationships between parents and children over multiple generations. 
The data is formatted as a list of (parent, child) pairs, where each individual is assigned a unique positive integer identifier.


For example, in this diagram, 6 and 8 have common ancestors of 4 and 14.


              15
             / \
        14  13  21
        |   |
1   2   4   12
\ /   / | \ /
 3   5  8  9
  \ / \     \
   6   7     11


pairs = [
   (1, 3), (2, 3), (3, 6), (5, 6), (5, 7), (4, 5),
   (15, 21), (4, 8), (4, 9), (9, 11), (14, 4), (13, 12),
   (12, 9), (15, 13)
]

3: [1,2]
4: [14]
6: [3,5,1,2,4,14]
8:[4,14]



Write a function that takes this data and the identifiers of two individuals as inputs and returns true if and only if they share at least one ancestor.


Sample input and output:


hasCommonAncestor(pairs, 3, 8)   => false
hasCommonAncestor(pairs, 5, 8)   => true
hasCommonAncestor(pairs, 6, 8)   => true
hasCommonAncestor(pairs, 6, 9)   => true
hasCommonAncestor(pairs, 1, 3)   => false
hasCommonAncestor(pairs, 3, 1)   => false
hasCommonAncestor(pairs, 7, 11)  => true
hasCommonAncestor(pairs, 6, 5)   => true
hasCommonAncestor(pairs, 5, 6)   => true
hasCommonAncestor(pairs, 3, 6)   => true
hasCommonAncestor(pairs, 21, 11) => true


n: number of pairs in the input