import sys
readline = sys.stdin.readline

 
def parorder(Edge, p):
    N = len(Edge)
    par = [0]*N
    dist = [0]*N
    par[p] = -1
    stack = [p]
    order = []
    visited = set([p])
    ast = stack.append
    apo = order.append
    while stack:
        vn = stack.pop()
        apo(vn)
        for w, vf in Edge[vn]:
            if vf in visited:
                continue
            visited.add(vf)
            par[vf] = vn
            dist[vf] = w
            ast(vf)
    return par, order, dist
 
def getcld(p):
    res = [[] for _ in range(len(p))]
    for i, v in enumerate(p[1:], 1):
        res[v].append(i)
    return res
 
 
 
 
MOD = 10**9+7
N = int(readline())
Edge = [[] for _ in range(N)]
for _ in range(N-1):
    a, b, w = map(int, readline().split())
    a -= 1
    b -= 1
    Edge[a].append((w, b))
    Edge[b].append((w, a))

P, L, dist = parorder(Edge, 0)

dsum = [0]*N
dsum2 = [0]*N
size = [1]*N
ans = 0
for l in L[:0:-1]:
    p = P[l]
    w = dist[l]
    dsum2[l] = (dsum2[l] + w*w%MOD*size[l] + 2*w*dsum[l])%MOD
    dsum[l] = (dsum[l] + w*size[l])%MOD
    ans = (ans + (dsum[l] + dsum[p])**2 - dsum[l]*dsum[l] - dsum[p]*dsum[p] + size[p]*dsum2[l] + size[l]*dsum2[p])%MOD
    dsum[p] = (dsum[p] + dsum[l])%MOD
    dsum2[p] = (dsum2[p] + dsum2[l])%MOD
    size[p] += size[l]
print(ans)