I'd Like a New Shade of Blue, Please

I have a bucket containing an amount of navy blue paint and I'd like to paint as many walls as possible. Create a function that returns the number of complete walls that I can paint, before I need to head to the shops to buy more.

• n is the number of square meters I can paint.
• w and h are the widths and heights of a single wall in meters.

Examples

how_many_walls(100, 4, 5) ➞ 5

how_many_walls(10, 15, 12) ➞ 0

how_many_walls(41, 3, 6) ➞ 2

Notes

• Don't count a wall if I don't manage to finish painting all of it before I run out of paint.
• All walls will have the same dimensions.
• All numbers will be positive integers.