There are 18 glasses in a display window of a shop including:
8 myopic (-1 to -8),
8 hypermetropic (+1 to +8),
2 sunglasses.
The myopic and hypermetropic ones have two labels. One of the lenses has either "-"
or "+" and the other has a number.
The sunglasses have black lenses with no labels.
Some of the rows of the display have "correct" mathematical operations in different
directions. The numbers outside of the display are the results of the operations
related to their directions. (The lenses of the sunglasses are ignored in these
operations). Locate the numbers and the operators onto the lenses and find all
glasses by joining the neighbour lenses.
X+Y = ?
