import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
from collections import deque
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

class UnionFind:
	def __init__(self, n):
		self.par = [i for i in range(n + 1)]
		self.rank = [0] * (n + 1)

	def find(self, x):
		if self.par[x] == x:
			return x
		else:
			self.par[x] = self.find(self.par[x])
			return self.par[x]

	def same_check(self, x, y):
		return self.find(x) == self.find(y)

	def union(self, x, y):
		x = self.find(x); y = self.find(y)
		if self.rank[x] < self.rank[y]:
			self.par[x] = y
		else:
			self.par[y] = x
			if self.rank[x] == self.rank[y]:
				self.rank[x] += 1

class Graph(object):
	def __init__(self):
		self.graph = defaultdict(list)

	def __len__(self):
		return len(self.graph)

	def add_edge(self, a, b):
		self.graph[a].append(b)

class BFS(object):
	def __init__(self, graph, s, N):
		self.g = graph.graph
		self.Q = deque(); self.Q.append(s)
		self.dist = [INF] * N; self.dist[s] = 0
		self.prev = [None] * N; self.prev[s] = -1
		while self.Q:
			v = self.Q.popleft()
			for i in self.g[v]:
				if self.dist[i] == INF:
					self.dist[i] = self.dist[v] + 1
					self.prev[i] = v
					self.Q.append(i)

def topologicalSort(outE, inE, N):

	W = [1] * N
	Q = deque()
	for i in range(N):
		if inE[i] == 0:
			Q.append(i)

	while Q:
		u = Q.popleft()
		for v in outE[u]:
			inE[v] -= 1
			W[v] += W[u]
			if inE[v] == 0:
				Q.append(v)
				

	return W

#処理内容
def main():
	N, M, X = getlist()
	UF = UnionFind(N)
	D = defaultdict(int)
	G = Graph()
	for i in range(M):
		x, y, z = getlist()
		x -= 1; y -= 1
		if not UF.same_check(x, y):
			UF.union(x, y)
			G.add_edge(x, y)
			G.add_edge(y, x)
			D[(10 ** 6) * x + y] = z
			D[(10 ** 6) * y + x] = z

	BF = BFS(G, 0, N)

	outE = defaultdict(list)
	inE = defaultdict(int)
	for i in range(1, N):
		a, b = i, BF.prev[i]
		outE[a].append(b)
		inE[b] += 1

	# print(outE)
	# print(inE)
	W = topologicalSort(outE, inE, N)
	# print(W)
	ans = 0
	for i in range(1, N):
		ans += (N - W[i]) * W[i] * pow(X, D[(10 ** 6) * i + BF.prev[i]], con)
		ans %= con

	print(ans)


if __name__ == '__main__':
	main()