import sys

sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = 10**9
# md = 998244353
md = 10**9+7

class UnionFind:
    def __init__(self, n):
        self.state = [-1]*n
        self.size_table = [1]*n
        # cntはグループ数
        self.cnt = n

    def root(self, u):
        stack = []
        while self.state[u] >= 0:
            stack.append(u)
            u = self.state[u]
        for v in stack: self.state[v] = u
        return u

    def same(self, u, v):
        return self.root(u) == self.root(v)

    def merge(self, u, v):
        u = self.root(u)
        v = self.root(v)
        if u == v: return False
        du = -self.state[u]
        dv = -self.state[v]
        if du < dv: u, v = v, u
        if du == dv: self.state[u] -= 1
        self.state[v] = u
        self.cnt -= 1
        self.size_table[u] += self.size_table[v]
        return True

    # グループの要素数
    def size(self, u):
        return self.size_table[self.root(u)]

n, m, x = LI()
xyz = LLI(m)

to = [[] for _ in range(n)]
uf = UnionFind(n)
xyz.sort(key=lambda x: x[2])
for u, v, z in xyz:
    u, v = u-1, v-1
    if not uf.merge(u, v): continue
    to[u].append((v, z))
    to[v].append((u, z))

size = [1]*n
ans = 0
stack = [(0, -1, True)]
while stack:
    u, par, first = stack.pop()
    if first:
        stack.append((u, par, False))
        for v, z in to[u]:
            if v == par: continue
            stack.append((v, u, True))
    else:
        for v, z in to[u]:
            if v == par: continue
            ans += size[v]*(n-size[v])*pow(x, z, md)%md
            size[u] += size[v]
            ans %= md

print(ans)