COCI '21 Contest 2 #2 Kutije
View as PDFMartin has  boxes labeled with positive integers from 
 to 
. Each box contains
a toy. The toys are also labeled with positive integers from 
 to 
 and in such a
way that initially the toy with label 
 is contained in the box with label 
.
From time to time, Martin calls one of his  friends to come over and hang out.
Once they meet up, his friend takes the toys out of the boxes and starts having fun
with them. In the meantime, Martin is more interested in the boxes. Once they
become bored, his friend puts the toys back into the boxes. However, he doesn't
necessarily put every toy in the box it was taken from.
Martin has noticed that each of his  friends scrambles the toys in the same way each time. More
precisely, each of his friends has his own array of 
 positive integers 
 which determines the way
he will put the toys back into the boxes. Every positive integer from 
 to 
 appears exactly once in this
array. His friend scrambles the toys in such a way that at the end of their meeting the box with label
 contains the toy that was in the box with label 
 at the start of their meeting. Notice that, because
every positive integer from 
 to 
 appears exactly once in the array, after all the toys are back in the
boxes, each box will again have exactly one toy in it.
Martin is now interested in answering questions of the following form: he is wondering whether it is
possible that the toy with label  (which is initially in box with label 
) can end up in the box with label 
via a sequence of meetups with his friends. A sequence of meetups means that Martin can call whichever
friends he wants and in any order. He can call a friend multiple times, or not at all. Martin is interested
in answering 
 such questions.
Input Specification
The first line contains positive integers , 
 and 
 - the number of boxes (also toys), the number of
Martin's friends and the number of questions, respectively.
The  of the following 
 lines contains an array of positive integers 
 that is used by Martin's
 friend for putting the toys back into the boxes. Each positive integer from 
 to 
 appears exactly
once in the array.
Each of the following  lines contains two positive integers 
 and 
 
 which represent a
question.
Output Specification
In  lines print the answer to the given questions, in order: 
DA if it is possible to get the toy in question to
the desired box, and NE otherwise.
Constraints
In every subtask, it holds that , 
.
| Subtask | Points | Constraints | 
|---|---|---|
| 1 | 15 | |
| 2 | 10 | DA, there exists a sequence of at most two meetups which achieves the desired result. | 
| 3 | 10 | |
| 4 | 35 | No additional constraints. | 
Sample Input 1
4 1 3
1 2 4 3
1 1
1 2
3 4
Sample Output 1
DA
NE
DA
Explanation for Sample Output 1
For the first question, the toy with label  is already initially in the box with label 
 so the answer is
immediately 
DA.
For the second question, notice that however many times Martin calls his friend over, the boxes with
labels  and 
 never change their content, so the answer is 
NE.
For the third question, notice that after each meetup, the contents of boxes  and 
 get exchanged, so
after only one meetup the toy with label 
 will find itself in box with label 
 and the answer is 
DA.
Sample Input 2
4 2 4
2 1 3 4
1 2 4 3
2 1
3 4
1 4
2 3
Sample Output 2
DA
DA
NE
NE
Sample Input 3
6 2 2
2 1 4 5 3 6
3 2 4 1 5 6
1 5
6 3
Sample Output 3
DA
NE
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