在八个城市之间建造电视微波中继站，如图是可行线路，弧旁数字为费用。试建在哪个城市可实现连通每个城市且费用为最低。-Between the eight cities in the construction of TV microwave relay station, it is feasible to figure lines, beside the figure for the cost of arc. Try to build cities in which to achieve connectivity in each city and the cost of the lowest.