import sys
from itertools import islice, product


def _solve(N, K, values):
    groups = list(range(K))
    ans = 0
    for g in product(groups, repeat=N):
        a = [[] for _ in range(K)]
        for k, v in zip(g, values):
            a[k].append(v)
        b = []
        try:
            for v in a:
                b.append(sum(v) / len(v))
        except ZeroDivisionError:
            continue
        average_d = -int(-(max(b) - min(b)))
        ans = max(ans, average_d)
    return ans


def solve(in_):
    N = int(next(in_))
    K = int(next(in_))
    values = [int(line) for line in islice(in_, N)]
    return _solve(N, K, values)
    

def main():
    answer = solve(sys.stdin.buffer)
    print(answer)


if __name__ == '__main__':
    main()