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const int MAX = 10000;
char visited[MAX];
vector<int> adj[MAX];
void dfs(int i) {
	visited[i] = 1;
	for (size_t j = 0 ; j < adj[i].size(); j++)
		if (! visited[ adj[i][j] ] )
			dfs( adj[i][j] );
}
int numConnectedComponents(int N) { // graph with N vertices
	int i, comps = 0;
	for (i = 0 ; i < N ; i++)
		visited[i] = 0;
	for (i = 0 ; i < N; i++)
		if (!visited[i]) {
			comps++;
			dfs(i);
		}
	return comps;
}