import sys
n=int(input())
arr=list(map(int,input().split()))
left,right=1,max(arr)
def check(mid):
    for i in arr:
        mid+=(mid-i)
        if mid<0:
            return 0
    return 1
while left<=right:
    mid=(left+right)//2
    if check(mid):
        right=mid-1
    else:
        left=mid+1
print(left)