D. Dropping Blocks - 2019 XCPC Newbie Selection #1 (South Pacific ICPC Regional Finals 2018) - ECNU Online Judge

你可以在这里下载。

单点时限: 2.0 sec

内存限制: 512 MB

样例

Input

4
3 3 2 1

Output

YES

Input

3
1 2 1

Output

YES

Input

5
1 2 1 2 1

Output

NO

Input

5
1 2 3 2 1

Output

NO

NaN

A. Aligned Typesetting B. Bad Keming C. Collecting Stars D. Dropping Blocks E. Explosive Wiring F. Far, Far Away G. Good Cable Management H. Hazardous Driving I. Interesting World of Arrays J. Judging Divisionals K. Knights and Dragons L. Laps