class DisjointSet:
    def __init__(self, nodes):
        self.parent = {x : x for x in nodes}
        self.rank = {x : 0 for x in nodes}

    def find(self, x):
        if self.parent[x] != x:
            self.parent[x] = self.find(self.parent[x])
        return self.parent[x]

    def add_node(self, x):
        if x not in self.parent:
            self.parent[x] = x
            self.rank[x] = 0

    def union(self, x, y):
        self.add_node(x)
        self.add_node(y)

        x_root = self.find(x)
        y_root = self.find(y)

        if x_root == y_root:
            return
        if self.rank[x_root] < self.rank[y_root]:
            x_root, y_root = y_root, x_root
        self.parent[y_root] = x_root
        self.rank[x_root] += self.rank[y_root]

def solve(edges):
    nodes = set()    
    for u, v, color in edges:
        nodes.add(u)
        nodes.add(v)

    ds = DisjointSet(nodes)
    for u, v, color in edges:
				# Two nodes can be connected through a black edge. Any other node connected through a black edge to these previous nodes will then belong to the same set of nodes all connected through black edges. A node that belongs to a black edge subset cannot be connected with another node belonging to the same or another black edge subset.
        if color == 'b':
            ds.union(u, v)
    
    subsets_sizes = {}
    for node in nodes:
        root = ds.find(node)
        subsets_sizes[root] = subsets_sizes.get(root, 0) + 1
    
    n = len(nodes)
    total_triplets = n * (n - 1) * (n - 2) // 6
    
    invalid_triplets = 0
    for size in subsets_sizes.values():
        if size >= 3:
            invalid_triplets += size * (size - 1) * (size - 2) // 6
        if size >= 2:
            invalid_triplets += size * (size - 1) // 2 * (n - size)
    
    valid_triplets = total_triplets - invalid_triplets
    return valid_triplets % (10**9 + 7)

n = int(input().strip())
edges = []
for _ in range(n - 1):
    u, v, color = input().strip().split()
    edges.append((int(u), int(v), color))

print(solve(edges))