import sys
readline = sys.stdin.readline


def decomposition(Edge, st = 0):
    N = len(Edge)
    bfsorder = [st]
    for i in range(N):
        vn = bfsorder[i]
        for vf in Edge[vn]:
            Edge[vf].remove(vn)
        bfsorder.extend(Edge[vn])
    
    sset = [0]*N
    for vn in bfsorder[::-1]:
        se = st = 0
        for vf in Edge[vn]:
            st |= sset[vf]&se
            se |= sset[vf]
        tmp = ~se & -(1<<st.bit_length())
        l = -tmp & tmp
        sset[vn] = (se|l) & -l
    
    return [(-l&l).bit_length()-1 for l in sset]

MOD = 10**9+7
N = int(readline())
Edge = [[] for _ in range(N)]
for _ in range(N-1):    
    u, v, w = map(int, readline().split())
    u -= 1
    v -= 1
    Edge[u].append((v, w))
    Edge[v].append((u, w))

levels = decomposition([[e[0] for e in ei] for ei in Edge])

ans = 0
size = [0]*N
ds = [0]*N
ds2 = [0]*N
dist = [0]*N
color = [0]*N
for lv in range(max(levels), 0, -1):
    used = [0]*N
    for i in range(N):
        if levels[i] > lv:
            used[i] = 1
    for vn in range(N):
        if levels[vn] != lv:
            continue
        used[vn] = 1
        dsum = 0
        ssum = 0
        stack = []
        for vf, w in Edge[vn]:
            if used[vf]:
                continue
            color[vf] = vf
            ssum += 1
            size[vf] = 1
            used[vf] = 1
            dist[vf] = w
            dsum = (dsum + w)%MOD
            ds[vf] = w
            ds2[vf]= w*w%MOD
            stack.append(vf)
        cs = stack[:]
        while stack:
            vn = stack.pop()
            for vf, w in Edge[vn]:
                if used[vf]:
                    continue
                used[vf] = 1
                c = color[vn]
                color[vf] = c
                dist[vf] = (dist[vn] + w)%MOD
                ds[c] = (ds[c] + dist[vf])%MOD
                dsum = (dsum + dist[vf])%MOD
                ds2[c] = (ds2[c] + dist[vf]*dist[vf])%MOD
                size[c] += 1
                ssum += 1
                stack.append(vf)

        ans = (ans + dsum*dsum)%MOD
        for r in cs:
            ans = (ans + ds2[r] + (ssum-size[r])*ds2[r] - ds[r]*ds[r])%MOD
print(ans)