How many shoes does a girl need?

My sister and I spent some time analysing our shoe collections. We concluded that the elements of the average female shoe collection are:

Flats, heels.
Flats in different colours to match different outfits, heels in different colours to match different outfits
Heels you can walk in, and heels you can't walk in
Boots
Ankle boots, knee length boots, sheepskin boots
Flat or low-heeled ankle boots to wear with jeans, high heeled ankle boots to wear with more formal trousers
Knee length boots with high heels and knee length boots which are flat or have low heels
High heeled boots with heels you can walk in and high heeled boots you can't walk in
Boots, ankle or knee length, in different colours to go with different outfits
Sandals
Evening shoes
The kitten-heeled mules that are out fashion but might come back into fashion
Shoes which the sales assistant said would stretch, but didn't
Shoes which don't go with anything else
Shoes that were in the sale and which were bought because they were so cheap but which you don't really like
Shoes that seemed like a good idea at the time
Ugly comfortable shoes
Shoes so beautiful and uncomfortable that they can only be worn when you only have to stand or walk for a minimum of three minutes.
Shoes to wear at the gym
Shoes to wear round the house
Shoes which you've forgotten about
Shoes that only exist in a partial dimension, having left the other one at a hotel

I hope this explains the matter more fully for members of the a man only needs three pairs of shoes brigade

UPDATE
I do in fact possess a pair of boots of the type used for walking in rough terrain which I was forced to buy for a journalistic assignment to a remote and mountainous part of Turkey several years ago. I also have a couple of pairs of flipflops, but I don't count any of these as shoes, more like protective gear such as umbrellas or earmuffs. Possession of Crocs voids the entire shoe collection.