I keep getting runtime error for my java code. Please help.

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

public class main {

public static void main(String[] args) throws java.lang.Exception {
	BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
	StringBuilder builder = new StringBuilder();
	int numCases = Integer.parseInt(reader.readLine().split(" ")[0]);
	reader.readLine();
	for (int i = 1; i <= numCases; i++){
		builder.append("Case " + i + ": ");
		int numPoints = Integer.parseInt(reader.readLine().split(" ")[0]);
		reader.readLine();
		float big = 0;
		int add = 0;
		for (int x = 1; x <= numPoints; x++){
			String temp = reader.readLine();
			reader.readLine(); 
			float a = Float.parseFloat(temp.split(" ")[0]);
			float b = Float.parseFloat(temp.split(" ")[1]);
			if (a*a + b*b > big){
				big = a*a + b*b;
				add = x;
			}
		}
		builder.append(add);
		builder.append(System.getProperty("line.separator"));
		builder.append(System.getProperty("line.separator"));
	}
	System.out.print(builder.toString());
	//get numcases
	//for numcases, add case # to builder, get numpoints
	//for numpoints find largest squares, add largest squares in builder
}

}

I'm not very well versed in python but it looks like instead of reading a line at a time, you just read the entire input and parsed after that?

If that isn't what you did could you explain, and why it works. Thanks again.