Find the Largest Common Substring between Two Strings using Java

/*
 * This file is for generating sample input data.
 */

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

public class Main {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

        // input
        String a = in.next();
        String b = in.next();

        // find the largest common substring between Strings a and b
        int n = a.length(), m = b.length(), sz = 0;
        String commonSubstring = "";
        for(int len = 1; len <= Math.min(n, m); len++) {
            for(int i = 0; i + len <= n; i++) {
                for(int j = 0; j + len <= m; j++) {
                    if(a.substring(i, i + len).equals(b.substring(j, j + len))) {
                        sz = Math.max(sz, len);
                        commonSubstring = a.substring(i, i + len);
                    }
                }
            }
        }

        // output
        System.out.println("Largest Common Substring: " + commonSubstring);
        System.out.println("String Size: " + sz);
    }

}