USACO Silver 2020 US Open - Social Distancing

Java

import java.util.*;
import java.io.*;

public class socdist{
	static int N, M;
	static Pair[] P;
	public static void main(String[] args) throws IOException{
		InputReader in = new InputReader("socdist.in");
		N = in.nextInt(); M = in.nextInt(); P = new Pair[M];
		for(int i = 0; i<M; i++){