// The task is to use breadth-first search to find out how many disjoint graphs there are
    static int friendCircles(String[] friends) {
        int[] visited = new int[friends.length]; // people we have checked
        int disjoint_graphs = 0;
        for (int start_node = 0; start_node < friends.length; start_noe++) {
            if(!visited[start_node]){
                LinkedList<Integer> queue = new LinkedList<>();
                queue.add(start_node);
                while(!queue.empty()){
                    Integer current_node = queue.remove();
                    for(int next_node = 0; next_node < friends[current_node].length();next_node++){
                        if(!visisted[next_node] && friends[current_node].charAt(next_node) == 'Y'){
                            queue.add(next)node);
                            visited[next_node] = true;
                        }
                    }
                }
                disjoint_graphs++;
            }
        }
        return disjoint_graphs;
    }