import sys
sys.setrecursionlimit(10**7)
input=sys.stdin.readline

n=int(input())
uvw=[list(map(int,input().split())) for _ in range(n-1)]

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):
  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)
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
  ret=0
  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+num1*sum0+nw*num0*num1
    tmp*=nw
    tmp%=mod
    ret+=tmp
    ret%=mod
    memo[(nv,v)]=num1,sum1
    ret+=dfs2(v,nv)
    ret%=mod
  return ret
print(dfs2(-1,0))