DBG((dbg, LEVEL_1, " %3d costs for root %+F color %d\n", curr->inevitable_costs, curr->nodes[0], root_col));
res += curr->inevitable_costs;
for (i=1; i<curr->node_count; ++i) {
DBG((dbg, LEVEL_1, " %3d costs for root %+F color %d\n", curr->inevitable_costs, curr->nodes[0], root_col));
res += curr->inevitable_costs;
for (i=1; i<curr->node_count; ++i) {