local mod = 1000000007
local mfl = math.floor

local function bmul(x, y)
  if x * y <= 1000000000000000 then return (x * y) % mod end
  local x1, y1 = mfl(x / 31623), mfl(y / 31623)
  local x0, y0 = x - x1 * 31623, y - y1 * 31623
  return (x1 * y1 * 14122 + (x1 * y0 + x0 * y1) * 31623 + x0 * y0) % mod
end

local function badd(x, y)
  return (x + y) % mod
end

local function bsub(x, y)
  return x < y and x - y + mod or x - y
end

local function modpow(src, pow)
  local res = 1
  while 0 < pow do
    if pow % 2 == 1 then
      res = bmul(res, src)
      pow = pow - 1
    end
    src = bmul(src, src)
    pow = mfl(pow / 2)
  end
  return res
end

local n, m, x = io.read("*n", "*n", "*n")
local ea, eb, ec = {}, {}, {}
for i = 1, m do
  ea[i], eb[i], ec[i] = io.read("*n", "*n", "*n")
end
local edge = {}
for i = 1, n do
  edge[i] = {}
end

local parent = {}
for i = 1, n do
  parent[i] = i
end

local function uf_findroot(idx)
  local idx_update = idx
  while parent[idx] ~= idx do
    idx = parent[idx]
  end
  while parent[idx_update] ~= idx do
    parent[idx_update], idx_update = idx, parent[idx_update]
  end
  return idx
end

local used = 0
for i = 1, m do
  local i1, i2, c = ea[i], eb[i], ec[i]
  local r1, r2 = uf_findroot(i1, parent), uf_findroot(i2, parent)
  parent[i1], parent[i2] = r1, r2
  if r1 ~= r2 then
    parent[r2] = r1
    parent[i2] = r1
    used = used + 1
    table.insert(edge[i1], i)
    table.insert(edge[i2], i)
    if used == n - 1 then break end
  end
end

local size = {}
for i = 1, n do
  parent[i] = 0
  size[i] = 1
end
local tasks = {1}
for i = 1, n do
  local src = tasks[i]
  for j = 1, #edge[src] do
    local ei = edge[src][j]
    local dst = ea[ei] == src and eb[ei] or ea[ei]
    if parent[src] ~= dst then
      parent[dst] = src
      table.insert(tasks, dst)
    end
  end
end
local ans = 0
for i = n, 1, -1 do
  local src = tasks[i]
  for j = 1, #edge[src] do
    local ei = edge[src][j]
    local dst = ea[ei] == src and eb[ei] or ea[ei]
    if parent[src] ~= dst then
      local csize = size[dst]
      ans = badd(ans, bmul(bmul(csize, n - csize), modpow(x, ec[ei])))
      size[src] = size[src] + csize
    end
  end
end
print(ans)