{
'A' => {
        'B' => 'C',
        'D' => 'E'
                    },
'F' => {
        'B' => 'G',
        'D' => 'H'
                    },
'I' => {
        'B' => 'G',
        'D' => 'H'
                    },
'J' => {
        'B' => 'C',
        'D' => 'F'
                    },

    }
}

##</code><code>##

 { 
   'B' => { 'C' => 2 ,'G' => 1}             # see G's and H's count is 1  Taking G and H's pair only once.  C is 2 because C, E and C,F do not make a pair, C comes twice and E and F once
   'D' => { 'E' => 1, 'H' => 1, 'F'=>1, }   # see H's count is 1
}