P3717 [AHOI2017 Middle School Division] cover

The following is a simplified version that does not change the meaning of the problem.

On an $n\times n$ grid (indexed from $1$), there are $m$ detectors, each with a detection radius $r$. Among these $n\times n$ points, how many points can be detected.

The first line contains $3$ integers $n,m,r$. Each of the next $m$ lines contains two integers $x,y$, representing the coordinates of the $i$-th detector.

Output the number of points that can be detected.

Constraints: $1\le n,m\le 100$. Translated by ChatGPT 5