I always get NZEC in JAVA, Pls help

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;

public class Main {

public static void main(String[] args) throws ArithmeticException, NumberFormatException, IOException{
	// TODO Auto-generated method stub
	int no = 10;
	for(int k=0; k<no;k++)
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String str = br.readLine();
		String str_1 = br.readLine();
		BigInteger t = new BigInteger(str);
		BigInteger p = new BigInteger(str_1);
		BigInteger div = new BigInteger("2");
		BigInteger Kl;
		Kl = t.add(p);
		Kl = Kl.divide(div);
		BigInteger Na;
		Na = t.subtract(p);
		Na = Na.divide(div);



What is the mistake in this ‘Throws exception’ and if I have to do ‘try catch’ what should I return in ‘catch’ to get AC.
Is there any other efficient input format other than buffered reader and scanner, which I can use in acm.