Problem:
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Largest Rectangle in a Histogram

A histogram is made of a number of contiguous bars, which have same width.

For a given histogram with $N$ bars which have a width of 1 and a height of $h_i$ = $h_1, h_2, ... , h_N$ respectively, find the area of the largest rectangular area.

Constraints

$1 \leq N \leq 10^5$

$0 \leq h_i \leq 10^9$

Input

The input is given in the following format.

$N$

$h_1$ $h_2$ ... $h_N$

Output

Print the area of the largest rectangle.

Sample Input 1

8
2 1 3 5 3 4 2 1

Sample Output 1

12

Sample Input 2

3
2 0 1

Sample Output 2

2

Solution in Python3 (judge verdict: Accepted)

n = int(input())
hs = list(map(int, input().split()))
stack = []
ans = 0

for i, h in enumerate(hs):
    j = -1
    while stack and stack[-1][1] > h:
        j, h2 = stack.pop()
        ans = max(ans, (i - j) * h2)
    if not stack or stack[-1][1] < h:
        stack.append((i if j == -1 else j, h))
ans = max(ans, max((n - j) * h2 for j, h2 in stack))

print(ans)