Two families are separated by a wall (grey=5) running down the center of the grid. Romeo (blue=4) is on the left side, Juliet (red=1) on the right. Each step they move closer to the wall. In the masked grid, they have both reached the wall — Romeo and Juliet are in adjacent cells on either side of the barrier. The wall between them at their meeting point cracks, changing from 5 to 2.