STPAR  Street Parade
For sure, the love mobiles will roll again on this summer's street parade. Each year, the organisers decide on a fixed order for the decorated trucks. Experience taught them to keep free a side street to be able to bring the trucks into order.
The side street is so narrow that no two cars can pass each other. Thus, the love mobile that enters the side street last must necessarily leave the side street first. Because the trucks and the ravers move up closely, a truck cannot drive back and reenter the side street or the approach street.
You are given the order in which the love mobiles arrive. Write a program that decides if the love mobiles can be brought into the order that the organisers want them to be.
Input
There are several test cases. The first line of each test case contains a single number n, the number of love mobiles. The second line contains the numbers 1 to n in an arbitrary order. All the numbers are separated by single spaces. These numbers indicate the order in which the trucks arrive in the approach street. No more than 1000 love mobiles participate in the street parade. Input ends with number 0.
Output
For each test case your program has to output a line containing a single word "yes" if the love mobiles can be reordered with the help of the side street, and a single word "no" in the opposite case.
Example
Sample input: 5 5 1 2 4 3 0 Sample output: yes
Illustration
The sample input reflects the following situation:
The five trucks can be reordered in the following way:
hide comments
shubhamptw:
20191012 08:55:20
confidence booster!


atanu_mt_ai_2:
20191003 19:36:00
What is the use of this line " Input ends with number 0" ? 

pprathamesh:
20190819 11:08:56
What will be the output for 1 2 3 4 5? 

alexyu:
20190731 10:16:39
easy problem but with terrible input format and confusing problem spec, wonder why it has such high quality rating 

shreyakjain14:
20190727 11:33:22
I have implemented this via circular queue. In my algorithm, I have find out the least element in set and then assigned the index of this element to front and rear is one minus of it. I had got results for the given samples. But I had got wrong answer when I submitted it . Can anyone help me to point out my mistake? Following is the link of my code:


anhtuan96a8:
20190717 04:27:14
2


shreyashlrn1:
20190713 20:38:43
try this


abhaypatro:
20190630 13:37:44
found the language to be a bit confusing , it took me a while to completely understand it.


sharath29:
20190623 08:46:07
AC in one go! 

utkarsh_bansal:
20190614 09:37:21
what is the order?

Added by:  Patryk Pomykalski 
Date:  20040701 
Time limit:  1s2s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: NODEJS PERL6 VB.NET 
Resource:  Swiss Olympiad in Informatics 2004 