Poj Solution 2524

http://poj.org/problem?id=2524

import java.io.BufferedInputStream;   
import java.util.Scanner;   
  
public class Main {   
  
    public static void main(String[] args) {   
        final int MAXSIZE = 50001;   
        Scanner scan = new Scanner(new BufferedInputStream(System.in));   
        int caseI = 1;
        int max = 0;   
        while (scan.hasNext()) {   
            int n = scan.nextInt();   
            int m = scan.nextInt();   
            if (n == 0 && m == 0) {   
                break;   
            }   
            DisjointSet dj = new DisjointSet(MAXSIZE);   
            int count = 0;   
            for (int i = 0; i < m; i++) {   
                int a = scan.nextInt();   
                int b = scan.nextInt();   
                int ra = dj.find(a);   
                int rb = dj.find(b);   
                if (ra != rb) {   
                    dj.union(ra, rb);   
                    count++;   
                }   
            }   
            max = n - count;   
            String result = "Case " + caseI + ": " + max;   
            System.out.println(result);   
            caseI++;   
        }   
    }   
}   
  
class DisjointSet {   
  
    protected int n;   
    protected int[] parent;   
    protected int[] rank;   
  
    public DisjointSet(int n) {   
        this.n = n;   
        init(n);   
    }   
  
    protected void init(int n) {   
        this.parent = new int[this.n + 1];   
        this.rank = new int[this.n + 1];   
        for (int i = 1; i <= n; i++) {   
            parent[i] = i;   
            rank[i] = 1;   
        }   
    }   
  
    protected int find(int x) {  
        if (parent[x] != x) {   
            parent[x] = find(parent[x]);   
        }   
        return parent[x];   
    }   
  
    protected void union(int ra, int rb) {   
        if (rank[ra] > rank[rb]) {   
            parent[rb] = ra;   
        } else if (rank[ra] < rank[rb]) {   
            parent[ra] = rb;   
        } else {   
            rank[rb]++;   
            parent[ra] = rb;   
        }   
    }   
}