import sys
sys.setrecursionlimit(10**6)
def input():
	return sys.stdin.buffer.readline()[:-1]

MOD = 10**9+7

class UnionFind():
	def __init__(self, size):
		self.table = [-1 for _ in range(size)]
		self.size = [1 for _ in range(size)]

	def find(self, x):
		while self.table[x] >= 0:
			if self.table[self.table[x]] >= 0:
				self.table[x] = self.table[self.table[x]]
			x = self.table[x]
		return x

	def unite(self, x, y):
		s1 = self.find(x)
		s2 = self.find(y)
		if s1 != s2:
			if self.table[s1] > self.table[s2]:
				self.table[s2] = s1
				self.table[s1] -= 1
				self.size[s1] += self.size[s2]
				self.size[s2] = 0
			else:
				self.table[s1] = s2
				self.table[s2] -= 1
				self.size[s2] += self.size[s1]
				self.size[s1] = 0
		return

n, m, X = map(int, input().split())
edge = []
for _ in range(m):
	x, y, z = map(int, input().split())
	edge.append((x-1, y-1, z))
edge.sort(key=lambda x: x[2])

uf = UnionFind(n)
adj = [[] for _ in range(n)]
for x, y, z in edge:
	if uf.find(x) != uf.find(y):
		uf.unite(x, y)
		adj[x].append((y, z))
		adj[y].append((x, z))

ans = 0
num = [1 for _ in range(n)]

def dfs(i, p):
	global ans
	for j, z in adj[i]:
		if j == p:
			continue
		dfs(j, i)
		ans += num[j] * (n - num[j]) * pow(X, z, MOD)
		ans %= MOD
		num[i] += num[j]
	return

dfs(0, -1)
print(ans)