import times, strutils, sequtils, math, algorithm, tables, sets, lists, intsets
import critbits, future, strformat, deques,heapqueue
template `max=`(x,y) = x = max(x,y)
template `min=`(x,y) = x = min(x,y)
template `mod=`(x,y) = x = x mod y
template scan2 = (scan(), scan())
template scan3 = (scan(), scan())
let read* = iterator: string {.closure.} =
    while true: (for s in stdin.readLine.split: yield s)
proc scan(): int = read().parseInt
proc scanf(): float = read().parseFloat
proc toInt(c:char): int =
    return int(c) - int('0')




proc modPow(x,n,md:int):int=
  var
    x = x
    n = n
  result = 1
  while n > 0:
    if (n and 1) > 0:
      result*=x
      result.mod=md
    x = (x^2).mod(md)
    n = n shr 1




proc solve()=
  var
    n = scan()
    m = scan()
    X = scan()
    #
    xyz = newseqwith(m,(scan()-1,scan()-1,scan()))
    md = 10^9+7
    roots = newseqwith(n,0)
  xyz = xyz.sortedByIt(it[2])
  
  for i in 0..<n:
    roots[i] = i
  
  proc find(x:int):int=
    if roots[x] == x:
      return x
    else:
      result = find(roots[x])
      roots[x] = result

  proc unite(x,y:int)=
    var
      rx = find(x)
      ry = find(y)
    if rx!=ry:
      roots[ry] = rx
    return

  var
    es = newseqwith(n,newseq[int]())
    cs = newseqwith(n,newseq[int]())
    res = 0
  
  for (x,y,z) in xyz:
    if find(x)!=find(y):
      es[x].add(y)
      es[y].add(x)
      cs[x].add(z)
      cs[y].add(z)
      unite(x,y)
  #echo es.join("\n")
  #echo ""
  #echo cs.join("\n")
  #echo  roots
  
  proc dfs(par,p:int):int=
    result = 1
    for (nxt,cost) in zip(es[p],cs[p]):
      if nxt == par:continue
      var t = dfs(p,nxt)
      res+=(((n-t)*t).mod(md)*modPow(X,cost,md)).mod(md)
      res.mod=md
      result+=t
  discard dfs(-1,0)
  echo res
    

  

  
  
    
solve()