n, k = map(int, input().split())
a = list(map(int, input().split()))

ok = min(a)
ng = 1 << 60
while abs(ok - ng) > 1:
  mid = (ok + ng) // 2

  offset = 0
  cnt = 0
  for i in range(n):
    cost = max(0, (mid - a[i] - offset + i) // (i + 1))
    cnt += cost
    offset += cost * (i + 1)

  if cnt <= k:
    ok = mid
  else:
    ng = mid

print(ok)