N, M = map(int, input().split())
A = list(map(int, input().split()))


def ok(n):
    rest = 0
    for a in A:
        a += rest
        if a < n:
            return False
        rest = a - n
    return True


l = 0
r = 10 ** 10
while r - l > 1:
    m = (r + l) // 2
    if ok(m):
        l = m
    else:
        r = m

print(l // M)