Sensor Network

Each sensor can communicate directly with sensors within Euclidean distance $d$. Given $n$ sensor coordinates, find a largest set in which every pair can communicate directly.

The first line has $n$ and $d$ ($1 \le n \le 100$, $1 \le d \le 10\,000$). The next $n$ lines give coordinates $x$, $y$ for sensors $1$ through $n$.

Print the maximum set size on the first line. Print the sensor indices on the second line. Any optimal set is accepted.