Sensor-Network

A wireless sensor network consists of autonomous sensors scattered in an environment.Input consists of single testcase. The first line of input contains n and d where n is the no.of sensors available and d is the maximum distance between distance that can communicate directly. Each of next n lines contains two integers x and y indicating the sensor coordinates.Output should be the maximum subset of sensors in which each pair of sensors can communicate directly.The first line of output contains the size of subset and second line contains indices of sensors in the subset.