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Задачі

Hippopotamus

Hippopotamus

Ліміт часу 1 секунда
Ліміт використання пам'яті 64 MiB

You think that your roof looks unpretty. So you opt for a new one, consisting of n consecutive long narrow boards. You have two types of boards: wooden ones and iron ones, giving you an amazing total of 2^n possible roofs.

But the safety should not be left aside. Having considered the weight and the cruising speed of a falling hippopotamus, you decide to have at least k iron boards among every m consecutive boards.

How many possibilities do you have?

Вхідні дані

The input file contains three integers, n, m and k, separated by spaces and/or line breaks. 1n60, 1m15, 0kmn.

Вихідні дані

Output the number of possibilities.

Приклад

Вхідні дані #1
10 2 1
Вихідні дані #1
144