6. [10 pts] Give an algorithm that counts the number of distinct ways a number N can be written as the sum of the numbers 1, 3, and 5 that runs in time O(N). Argue that your algorithm is correct. (Note that N is the value of the number, not the input size.) For example, 3+ 111 - 11+3+1 - 5+1 So, for N-6 the answer is 8