A B n1
A B n2
A C n1
D E n2
D E n4
D F n1

##</code><code>##

{
 A => {
   B => [
      n1,
      n2,
    ],
   C => [
      n1,
    ]
  },
 D => {
   E => [
      n2,
      n4,
    ],
   F => [
      n1,
    ]
  }
}
##</code><code>##

{
 A => {
   count => 3,
   B => {
    count => 2,
    [
      n1,
      n2,
    ],
   },
   C => {
    count => 1,   
    [
      n1,
    ]
   }
  },etc.