n,k = map(int,input().split())
a = list(map(int,input().split()))
ok = 0; ng = max(a)+k+1
while ng-ok>1:
    mid = (ok+ng)//2
    b = a[:]; c = s = 0
    for i in range(1,n+1):
        d = mid-a[i-1]-s
        if d<=0: continue
        r = (d-1+i)//i
        c += r; s += r*i
    if c<=k: ok = mid
    else: ng = mid
print(ok)