def everynth(arr, n):
    ans = [[] for i in range(n)]
    for i in range(len(arr)):
        ans[i % n].append(arr[i])
    return ans

print(everynth(['a','b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n'], 3))