10583 - Ubiquitous Religions, uva

#include<iostream>
#include<cstdio>
#include<algorithm>
#define db(a) cout << #a << " = " << a << endl
#define db2(a, b) cout << #a << " = " << a << " " << #b << " = " << b << endl
#define db3(a, b, c) cout << #a << " = " << a << " " << #b << " = " << b << " " << #c << " = " << c << endl
#define MAX 50001
using namespace std;
int P[MAX], mejor[MAX];
int find(int i) { return P[i] == -1 ? i : P[i] = find(P[i]); }
void join(int i, int j) { if (find(i) != find(j)) P[find(i)] = find(j);}
void init(int n) { fill(P, P + n, -1);}
int main() {
 int n, m, a, b, cont = 1;
 while (scanf("%d %d", &n, &m) != EOF && (n || m)) {
  init(n + 1);
  for (int i = 0; i < m; i++) {
   scanf("%d %d", &a, &b);
   join(a, b);
  }
  int res = 0;
  for (int i = 1; i < n + 1; i++) res += find(i) == i;
  printf("Case %d: %d\n",cont++ , res);
 }
 return 0;
}