from heapq import nlargest,heapify
def solve():
n=int(input());a=list(map(int,input().split()))
ind=a.index(max(a))
if a[:ind]==sorted(a[:ind]) and a[ind+1::]==sorted(a[ind+1::],reverse=True):print("YES")
else:print("NO")
solve()583. Delete Operation for Two Strings | 518. Coin Change 2 |
516. Longest Palindromic Subsequence | 468. Validate IP Address |
450. Delete Node in a BST | 445. Add Two Numbers II |
442. Find All Duplicates in an Array | 437. Path Sum III |
436. Find Right Interval | 435. Non-overlapping Intervals |
406. Queue Reconstruction by Height | 380. Insert Delete GetRandom O(1) |
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377. Combination Sum IV | 322. Coin Change |
307. Range Sum Query - Mutable | 287. Find the Duplicate Number |
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274. H-Index | 260. Single Number III |
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215. Kth Largest Element in an Array | 198. House Robber |
153. Find Minimum in Rotated Sorted Array | 150. Evaluate Reverse Polish Notation |