import sys, math
input = lambda: sys.stdin.readline()[:-1]
def MI(): return map(int, input().split())
inf = 10**18

class BIT:
    def __init__(self, n):
        self.size = n
        self.n0 = 1 << (n.bit_length() - 1)
        self.tree = [0] * (n + 1)
        
    def sum(self, i):
        i += 1
        s = 0
        while i > 0:
            s += self.tree[i]
            i -= i & -i
        return s
        
    def add(self, i, x):
        i += 1
        while i <= self.size:
            self.tree[i] += x
            i += i & -i
    
    def range_sum(self, l, r):
        return self.sum(r - 1) - self.sum(l - 1)
    
    def get(self, i):
        return self.sum(i) - self.sum(i - 1)
    
    def lower_bound(self, x):
        pos = 0
        plus = self.n0
        while plus > 0:
            if pos + plus <= self.size and self.tree[pos + plus] < x:
                x -= self.tree[pos + plus]
                pos += plus
            plus //= 2
        return pos

# https://ikatakos.com/pot/programming_algorithm/data_structure/binary_indexed_tree
# 区間加算 / 区間和
class RangeUpdate:
    def __init__(self, n):
        self.p = BIT(n)
        self.q = BIT(n)
     
    def add(self, l, r, x):
        self.p.add(l, -x * (l-1))
        self.p.add(r-1, x * (r-1))
        self.q.add(l, x)
        self.q.add(r-1, -x)
     
    def get_sum(self, l, r):
        sum_p = self.p.sum(r-1) + self.q.sum(r-1) * (r-1)
        sum_q = self.p.sum(l-1) + self.q.sum(l-1) * (l-1)
        return sum_p - sum_q

n,k = MI()
a = list(MI())

def isok(mid):
    bit = RangeUpdate(n)
    for i in range(n):
        bit.add(i, i+1, a[i])

    cnt = 0
    for left in range(n):
        mn = bit.get_sum(left, left+1)
        if mn<mid:
            tmp = -(-(mid-mn)//(left+1))
            cnt += tmp
            bit.add(left, n, (left+1)*tmp)
    
    if cnt<=k:
        return True
    else: return False

l,r = -1, 2*10**15
while abs(l-r)>1:
    mid = (l+r)//2
    if isok(mid): l = mid
    else: r = mid
print(l)