# Enter your code here. Read input from STDIN. Print output to STDOUT

n = int(raw_input())
a = map(int, raw_input().split())
while n > 1:
    b = []
    for k in range(len(a)):
        for i in range(len(a)-k):
            j = i+k
            b = b + [max(a[i:j+1])]
    a = b
    n -= 1
    #print a
print sum(a)