April Fools Contest 2018

这个比赛不正经，但是我可以一本正经的写代码啊

A. Quirky Quantifiers

time limit per test

2 seconds

memory limit per test

64 megabytes

input

standard input

output

standard output

Input

The input contains a single integer a (10 ≤ a ≤ 999).

Output

Output 0 or 1.

Examples

input

Copy

13

output

1

input

Copy

927

output

1

input

Copy

48

output

0

---

蛇皮，题目什么都没，0和1，反正是A，猜奇偶吧

#include<bits/stdc++.h>
using namespace std;
int main()
{int n;cin>>n;cout<<(n&1);return 0;
}

B. A Map of the Cat

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

If you have ever interacted with a cat, you have probably noticed that they are quite particular about how to pet them. Here is an approximate map of a normal cat.

However, some cats won't tolerate this nonsense from the humans. Here is a map of a grumpy cat.

You have met a cat. Can you figure out whether it's normal or grumpy?

Interaction

This is an interactive problem. Initially you're not given any information about the cat. Instead, the cat is divided into ten areas, indexed from 0 to 9.

In one query you can choose which area you'll pet and print the corresponding index to standard out. You will get the cat's response, as depicted on the corresponding map, via standard in. For simplicity all responses are written in lowercase.

Once you're certain what type of cat you're dealing with, output "normal" or "grumpy" to standard out.

Note

Please make sure to use the stream flushing operation after each query in order not to leave part of your output in some buffer.

B就直接阅读理解了么，这个脑洞大，让我组合的应该，不做这个

C. Ravioli Sort

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Everybody knows of spaghetti sort. You decided to implement an analog sorting algorithm yourself, but as you survey your pantry you realize you're out of spaghetti! The only type of pasta you have is ravioli, but you are not going to let this stop you...

You come up with the following algorithm. For each number in the array ai, build a stack of ai ravioli. The image shows the stack for ai = 4.

Arrange the stacks in one row in the order in which the corresponding numbers appear in the input array. Find the tallest one (if there are several stacks of maximal height, use the leftmost one). Remove it and add its height to the end of the output array. Shift the stacks in the row so that there is no gap between them. Repeat the procedure until all stacks have been removed.

At first you are very happy with your algorithm, but as you try it on more inputs you realize that it doesn't always produce the right sorted array. Turns out when two stacks of ravioli are next to each other (at any step of the process) and differ in height by two or more, the top ravioli of the taller stack slides down on top of the lower stack.

Given an input array, figure out whether the described algorithm will sort it correctly.

Input

The first line of input contains a single number n (1 ≤ n ≤ 10) — the size of the array.

The second line of input contains n space-separated integers ai (1 ≤ ai ≤ 100) — the elements of the array.

Output

Output "YES" if the array can be sorted using the described procedure and "NO" if it can not.

Examples

input

Copy

3
1 2 3

output

YES

input

Copy

3
3 1 2

output

NO

Note

In the second example the array will change even before the tallest stack is chosen for the first time: ravioli from stack of height 3 will slide on the stack of height 1, and the algorithm will output an array {2, 2, 2}.

做nmh，读不懂，我还是补线段树好了