from typing import List
import sys
sys.setrecursionlimit(10**8)

class UnionFind:
    """0-indexed"""
    def __init__(self, n):
        self.n = n
        self.parent = [-1] * n
        self.__group_count = n

    def unite(self, x, y) -> bool:
        """xとyをマージ"""
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return False

        self.__group_count -= 1

        if self.parent[x] > self.parent[y]:
            x, y = y, x

        self.parent[x] += self.parent[y]
        self.parent[y] = x
        return True

    def is_same(self, x, y) -> bool:
        """xとyが同じ連結成分か判定"""
        return self.root(x) == self.root(y)

    def root(self, x) -> int:
        """xの根を取得"""
        if self.parent[x] < 0:
            return x
        else:
            # 経路圧縮あり
            # self.parent[x] = self.root(self.parent[x])
            # return self.parent[x]
            # 経路圧縮なし
            return self.root(self.parent[x])

    def size(self, x) -> int:
        """xが属する連結成分のサイズを取得"""
        return -self.parent[self.root(x)]

    def all_sizes(self) -> List[int]:
        """全連結成分のサイズのリストを取得 O(N)"""
        sizes = []
        for i in range(self.n):
            size = self.parent[i]
            if size < 0:
                sizes.append(-size)
        return sizes
    
    def members(self, x) -> List[int]:
        """xが属するグループのリストを返す O(N)"""
        mem = []
        r = self.root(x)
        for i in range(self.n):
            if self.root(i) == r:
                mem.append(i)
        return mem

    def groups(self) -> List[List[int]]:
        """全連結成分の内容のリストを取得 O(N・α(N))"""
        groups = dict()
        for i in range(self.n):
            p = self.root(i)
            if not groups.get(p):
                groups[p] = []
            groups[p].append(i)
        return list(groups.values())

    @property
    def group_count(self) -> int:
        """連結成分の数を取得 O(1)"""
        return self.__group_count

N, M, X = map(int, input().split())
uf = UnionFind(N)
G = [list() for _ in range(N)]
for i in range(M):
    x, y, z = map(int, input().split())
    x-=1;y-=1
    if uf.is_same(x,y):continue
    uf.unite(x,y)
    G[x].append((y,z))
    G[y].append((x,z))

sub_tree = [0]*N
def dfs(v, p):
    for next_v,_ in G[v]:
        if next_v == p:
            continue
        dfs(next_v, v)
    sub_tree[v] = 1
    for c,_ in G[v]:
        if c== p:
            continue
        sub_tree[v] += sub_tree[c]

res = 0
mod = 10**9+7
def dfs2(v, p):
    for nex, cost in G[v]:
        if nex==p:continue
        global res
        res += pow(X,cost,mod)*(sub_tree[nex]*(N-sub_tree[nex]))
        res %= mod
        dfs2(nex,v)
dfs(0,-1)
dfs2(0,-1)
print(res)