Chef and math

Chef's team is going to participate at the legendary math battles. One of the main task in the competition is to calculate the number of ways to create a number by adding some Chefonacci numbers. A number is called a Chefonacci number if it is an element of Chefonacci sequence defined as follows. f(0) = 1; f(1) = 2; For i > 1 : f(i) = f(i - 1) + f(i - 2) Chef asked you to help him with t