A windowsill must have at least 1 potted flowers.

However, the number of flowerpots placed on each windowsill is different.

Subtract the flowers from the other three windowsills, and the other three windowsills add up to the smallest, so one windowsill has the most.

So the number of the other three windowsills is 1, 2, 3, which adds up to the smallest.

Max: 22- 1-2-3= 16.

I hope it helps you!