Problem Statement

There is a grid with $H$ rows and $W$ columns. Let $(r,c)$ denote the square at the $r$-th row from the top and $c$-th column from the left.

We have $N$ pieces. For the $i$-th piece, we can choose to do one of the following:

• Put it at a square $(r,c)$ such that Ai​≤r≤Ci​ and Bi​≤c≤Di​.
• Do not put it on the grid.

However, we cannot put two pieces in the same row or the same column.

At most how many pieces can we put on the grid?

Constraints

• $1\le H,W,N\le 100$
• 1≤Ai​≤Ci​≤H
• 1≤Bi​≤Di​≤W
• All values in input are integers.

Sample Input 1 Copy

2 3 3
1 1 2 2
1 2 2 3
1 1 1 3

Sample Output 1 Copy

2

By putting the first piece at $(1,1)$, the second piece at $(2,2)$, and not putting the third piece on the grid, we can put two pieces on the grid. We cannot put three, so we should print $2$.

Sample Input 2 Copy

5 5 3
1 1 5 5
1 1 4 4
2 2 3 3

Sample Output 2 Copy

3