MOD = 10 ** 9 + 7


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

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

    # 併合
    def unite(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return
        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

    # 同じ集合に属するか判定
    def same_check(self, x, y):
        return self.find(x) == self.find(y)


n, m, x = map(int, input().split())
uf = UnionFind(n)
g = [[] for _ in range(n)]
ans = 0
for _ in range(m):
    a, b, c = map(int, input().split())
    if not uf.same_check(a - 1, b - 1):
        uf.unite(a - 1, b - 1)
        g[a - 1].append((b - 1, pow(x, c, MOD)))
        g[b - 1].append((a - 1, pow(x, c, MOD)))
d = [-2] * n
c = [1] * n
s = [0]
ans = 0
while s:
    p = s.pop()
    if d[p] == -2:
        s.append(p)
        d[p] = -1
        for node, cost in g[p]:
            if d[node] == -2:
                s.append(node)
    else:
        d[p] = 0
        for node, cost in g[p]:
            if d[node] >= 0:
                c[p] += c[node]
                ans += (n - c[node]) * c[node] * cost
print(ans % MOD)