def build(G, T):
    for x in T:
        if not T.has(x):
            continue
        for y in G:
            if T.has(y):
                continue
            if G[(x, y)] == 'Y':
            T.add((x, y, 'Y'));
            checkResult = CheckLoop(T)
            if(checkResult.hasXEdge):
                if(xCount < T.xCount):
                    T.remove(checkResult.getXEdge())
                    return
                else
                    T.remove((x, y, 'Y'))
    return

def buildSpanningTree(G, xCount):
    T = MakeSpanningForest(G)

    for i in range(0, G.size):
        rebuild(G, T)