import sys
sys.setrecursionlimit(10**7)
input=sys.stdin.readline
def main1(n,uvw):
  ki=[[] for _ in range(n)]
  for u,v,w in uvw:
    u,v=u-1,v-1
    ki[u].append([v,w])
    ki[v].append([u,w])
  mod=10**9+7
  memo={}
  def dfs1(p,v):# 
    if (p,v) in memo:return memo[(p,v)]
    numv,sumv=1,0
    for nv,nw in ki[v]:
      if nv==p:continue
      num_,sum_=dfs1(v,nv)
      numv+=num_
      sumv+=sum_+num_*nw
      sumv%=mod
    memo[(p,v)]=numv,sumv
    return numv,sumv
  dfs1(-1,0)
  ans=[0]
  def dfs2(p,v):
    snumv,ssumv=1,0
    for nv,nw in ki[v]:
      num_,sum_=memo[(v,nv)]
      snumv+=num_
      ssumv+=sum_+num_*nw
      ssumv%=mod
    for nv,nw in ki[v]:
      if nv==p:continue
      num0,sum0=memo[(v,nv)]
      num1,sum1=snumv-num0,ssumv-sum0-nw*num0
      num1,sum1=num1%mod,sum1%mod
      tmp=num0*sum1%mod+num1*sum0%mod+nw*num0*num1%mod
      tmp%=mod
      tmp*=nw
      tmp%=mod
      ans[0]+=tmp
      ans[0]%=mod
      memo[(nv,v)]=num1%mod,sum1%mod
      dfs2(v,nv)
  dfs2(-1,0)
  #print(memo)
  return ans[0]
if __name__=='__main__':
  n=int(input())
  uvw=[list(map(int,input().split())) for _ in range(n-1)]
  ret1=main1(n,uvw)
  print(ret1)