Untitled

          U = {Store 1, Store 2, Store 3, ..., Store 13, Store 14}
   
          A = {Store 1, Store 2, Store 3, Store 7, Store 11}
         ___
        /   \
       /  A  \
       \___/
   
          B = {Store 7, Store 8, Store 11, Store 12, Store 14}
         ___
        /   \
       /  B  \
       \___/
   
          C = {Store 1, Store 4, Store 6, Store 10, Store 11}
         ___
        /   \
       /  C  \
       \___/