bool isSafe(int node, int c) {
    for (int i = 0; i < v[node].size(); i++)
        if (v[node][i] && c == color[i]) {
            return false;
        }
    return true;
}

bool graph_coloring(int m, int node) {
    for (auto i : v[node]) {
        for (int c = 1; c <= m; c++) {
            if (isSafe(node, c)) {
                color[node] = c;
                if (graph_coloring(m, i)) {
                    return true;
                }
                color[node] = 0;
            }
        }
    }
    return false;
}