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 \textbf{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 \textbf{k} iron boards among every \textbf{m} consecutive boards. How many possibilities do you have? \InputFile The input file contains three integers, \textbf{n}, \textbf{m} and \textbf{k}, separated by spaces and/or line breaks. \textbf{1} ≤ \textbf{n} ≤ \textbf{60}, \textbf{1} ≤ \textbf{m} ≤ \textbf{15},\textbf{0} ≤ \textbf{k} ≤ \textbf{m} ≤ \textbf{n}. \OutputFile Output the number of possibilities.