naive pattern matching

public class NaivePatternMatching {

    /**
     * @param args the command line arguments
     */

    public static int search(String txt, String pat)
    {
        int M = pat.length();
        int N = txt.length();

        int index = -1;
        /* A loop to slide pat one by one */
        for (int i = 0; i <= N - M; i++) {

            int j;

            /* For current index i, check for pattern
              match */
            for (j = 0; j < M; j++) {
                if (txt.charAt(i + j) != pat.charAt(j))
                    break;
            }
            if (j == M) // if pat[0...M-1] = txt[i, i+1, ...i+M-1]
                index = i;
        }
        return index;
    }

    public static void main(String[] args) {
        // TODO code application logic here
        Scanner sc = new Scanner(System.in);

        String txt;
        String pat;

        System.out.println("Enter the main string: ");
        txt = sc.nextLine();
        System.out.println("Enter the pattern/finding string: ");
        pat = sc.nextLine();

        int ans = search(txt, pat);

        if(ans==-1)System.out.println("Pattern not found!!");
        else System.out.println("Pattern found at position "+ans+1);

    }
}