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

def check(n):
    SUM = sum(max(i-n,0) for i in A)
    return SUM <= K

ng,ok = -1,10**10
while(ok - ng > 1):
    mid = (ok+ng)//2
    if(check(mid)):
        ok = mid
    else:
        ng = mid
print(ok * 2)