### 2011 Canadian Computing Competition, Stage 2

## Day 1, Problem 3: Spies Like Us

The Ultrasecret Spy Organization is very concerned about recent leads concerning a secret conspiracy involving the use of the Comic Sans font.

In order to avoid groupthink, the Ultrasecret Spy Organization has decided to
divide its agents in two groups. Each of the two groups will carry its own
investigation. However, occasionally interaction between members of different
groups will happen through some previously designated contact points
(*i.e.*, two people on different teams that are allowed to speak with each
other in special circumstances). This has to be made in a way that preserves the
fact that there is not much communication between the teams. To make this rule
more exact, two people on the same team can have no more than one common contact
on the other team.

You are given a plan for the contact points between the two groups. Your task is to determine whether this actually satisfies the constraint that two people on the same team can have no more than one common contact in the other team.

### Input Format

The first line of the input file will contain two space-separated integers
`N` and `M`
(1 ≤ `N`, `M` ≤ 2000). They
represent the number of people in each of the teams. The next line will contain
an integer `K`
(0 ≤ `K` ≤ `NM`). Each of the
following `K` lines will contain two integers, `i`
(1 ≤ `i` ≤ `N`) and `j`
(1 ≤ `j` ≤ `M`). This input will
represent that person `i` of the first team and person `j` of
the second team are allowed to communicate with each other.

Note: For test cases worth 25% of the marks, you may assume
`N`, `M` ≤ 200.

### Output Format

For each input, you will output one line. Its content will be
`YES`

, if the proposal satifies the constraint that two people on the
same team can have no more than one common contact on the other team, and
`NO`

otherwise.

### Sample Input

5 3 4 1 1 2 1 3 1 4 1

### Sample Output

YES

All Submissions

Best Solutions

**Point Value:** 10 (partial)

**Time Limit:** 2.00s

**Memory Limit:** 256M

**Added:** Jun 06, 2011

**Languages Allowed:**

C++03, PAS, C, HASK, ASM, RUBY, PYTH2, JAVA, PHP, SCM, CAML, PERL, C#, C++11, PYTH3

## Comments (Search)

It's quiet in here...