import math


def judge(mid):
    cnt = 0
    nokori = k
    for i in range(n):
        if mid > a[i] + cnt:
            # print(cnt,(mid - a[i] - cnt))
            nokori -= math.ceil((mid - a[i] - cnt) / (i + 1))
            cnt += (i + 1) * math.ceil((mid - a[i] - cnt) / (i + 1))
    if nokori < 0:
        return False
    else:
        return True


n, k = map(int, input().split())
a = list(map(int, input().split()))
ok = 0
ng = 10 ** 18
while abs(ok - ng) > 1:
    mid = (ok + ng) // 2
    if judge(mid):
        ok = mid
    else:
        ng = mid
print(ok)