import sys
sys.setrecursionlimit(10 ** 8)

N,M,X = map(int,input().split())
G = [[] for _ in range(N+1)]
P = 10 ** 9 + 7
edge = []
parent = list(range(N+1))
def find(i):
    if parent[i] == i:return i
    parent[i] = find(parent[i])
    return parent[i]
def unite(i,j):
    I = find(i)
    J = find(j)
    if I == J:return False
    parent[I] = J
    parent[i] = J
    return True
def isSame(i,j):
    return find(i) == find(j)

for _ in range(M):
    x,y,z = map(int,input().split())
    if isSame(x,y):
        continue
    else:
        unite(x,y)
        G[x].append(y)
        G[y].append(x)
        edge.append((x,y,z))
child = [1] * (N + 1)
"""
def dfs(now = 1,p = 0):
    for v in G[now]:
        if v == p:continue
        dfs(v,now)
        child[now] += child[v]
dfs()
"""
stack = [(1,0)]
order = []
while stack:
    now,p = stack.pop()
    order.append((now,p))
    for v in G[now]:
        if v == p:continue
        stack.append((v,now))
for v,p in order[::-1]:
    if p == 0:continue
    child[p] += child[v]
    
ans = 0
for x,y,z in edge:
    if child[x] > child[y]:
        x,y = y,x
    ans = (ans + child[x] * (N-child[x]) * pow(X,z,P)) % P
print(ans)