import sys
input = sys.stdin.readline

class Unionfind:
    def __init__(self, n):
        self.par = [-1]*n
        self.rank = [1]*n
    
    def root(self, x):
        r = x
        
        while not self.par[r]<0:
            r = self.par[r]
        
        t = x
        
        while t!=r:
            tmp = t
            t = self.par[t]
            self.par[tmp] = r
        
        return r
    
    def unite(self, x, y):
        rx = self.root(x)
        ry = self.root(y)
        
        if rx==ry:
            return
        
        if self.rank[rx]<=self.rank[ry]:
            self.par[ry] += self.par[rx]
            self.par[rx] = ry
            
            if self.rank[rx]==self.rank[ry]:
                self.rank[ry] += 1
        else:
            self.par[rx] += self.par[ry]
            self.par[ry] = rx
    
    def is_same(self, x, y):
        return self.root(x)==self.root(y)
    
    def count(self, x):
        return -self.par[self.root(x)]

def dfs():
    stack = [(0, -1)]
    in_order = [-1]*N
    in_order_now = 0
    par = [-1]*N
    size = [1]*N
    
    while stack:
        v, pv = stack.pop()
        in_order[v] = in_order_now
        in_order_now += 1
        
        for nv in G[v]:
            if nv==pv:
                continue
            
            par[nv] = v
            stack.append((nv, v))
    
    vs = [(in_order[v], v) for v in range(1, N)]
    vs.sort(reverse=True)
    
    for _, v in vs:
        size[par[v]] += size[v]
    
    return size
    
N, M, X = map(int, input().split())
uf = Unionfind(N)
G = [[] for _ in range(N)]
edges = []

for _ in range(M):
    x, y, z = map(int, input().split())
    
    if not uf.is_same(x-1, y-1):
        uf.unite(x-1, y-1)
        G[x-1].append(y-1)
        G[y-1].append(x-1)
        edges.append((x-1, y-1, z))

size = dfs()
ans = 0
MOD = 10**9+7

for x, y, z in edges:
    m = min(size[x], size[y])
    ans += m*(N-m)*pow(X, z, MOD)
    ans %= MOD

print(ans)