MOD = 10 ** 9 + 7

class UnionFind:
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n
        self.group = n

    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)

        if x == y:
            return
        self.group -= 1
        if self.parents[x] > self.parents[y]:
            x, y = y, x

        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

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

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return self.group

    def all_group_members(self):
        dic = {r:[] for r in self.roots()}
        for i in range(self.n):
            dic[self.find(i)].append(i)
        return dic

    def __str__(self):
        return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())


n, m, X = map(int, input().split())
UF = UnionFind(n)
edges = [[] for _ in range(n)]
for _ in range(m):
    x, y, z = map(int, input().split())
    x -= 1
    y -= 1
    if not UF.same(x, y):
        UF.union(x, y)
        edges[x].append((y, z))
        edges[y].append((x, z))

ans = 0
route = [0]
stack = [0]
used = [False] * n
used[0] = True
while stack:
    pos = stack.pop()
    for npos, _ in edges[pos]:
        if used[npos]:
            continue
        used[npos] = True
        stack.append(npos)
        route.append(npos)

size = [1] * n
used = [False] * n
for pos in route[::-1]:
    used[pos] = True
    for npos, z in edges[pos]:
        if not used[npos]:
            continue
        ans += pow(X, z, MOD) * size[npos] * (n - size[npos])
        ans %= MOD
        size[pos] += size[npos]
print(ans)