class UnionFind {
    int[] parent;
    int[] size;

    UnionFind(int n) {
        parent = new int[n];
        size = new int[n];
        for (int i = 0; i < n; i++) {
            parent[i] = i;
            size[i] = 1;
        }
    }

    int find(int node) {
        if (parent[node] != node) parent[node] = find(parent[node]);
        return parent[node];
    }

    boolean union(int a, int b) {
        int ra = find(a), rb = find(b);
        if (ra == rb) return false;
        if (size[ra] < size[rb]) { int t = ra; ra = rb; rb = t; }
        parent[rb] = ra;
        size[ra] += size[rb];
        return true;
    }
}