Zadacha_1

def isAnswer(array, k, checked):
    last = -1
    count = 0
    for i in range(len(array)):
        if last == -1 or array[i] - array[last] >= checked:
            count += 1
            last = i
    return count >= k
    


def find(array, k):
    l = 0
    r = 10**9
    while l + 1 < r:
        m = (l + r)//2
        if isAnswer(array, k, m):
            l = m
        else:
            r = m
    return l


n, k = list(map(int, input().split()))
st_array = list(map(int, input().split()))
        
print(find(st_array, k))