import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(1000005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = -1-(-1 << 63)
md = 10**9+7
# md = 998244353

n = II()
to = [[] for _ in range(n)]
for _ in range(n-1):
    u, v, w = LI1()
    w += 1
    to[u].append((v, w))
    to[v].append((u, w))

def dfs(root=0):
    uu, stack = [], [root]
    while stack:
        u = stack.pop()
        uu.append(u)
        for v, w in to[u]:
            if v == parent[u]: continue
            ww[v] = w
            parent[v] = u
            depth[v] = depth[u]+1
            stack.append(v)
    return uu

parent, depth, ww = [-1]*n, [0]*n, [0]*n
uu = dfs()

dp = [[1, 0, 0] for _ in range(n)]
ans = 0
for u in uu[:0:-1]:
    w = ww[u]
    w2 = w*w%md
    v = parent[u]
    dpu = dp[u]
    dpv = dp[v]

    ans += dpu[2]*dpv[0]%md+dpv[2]*dpu[0]%md+w2*dpu[0]%md*dpv[0]%md+2*dpu[1]*dpv[1]%md+2*w*(
                dpu[1]*dpv[0]%md+dpv[1]*dpu[0]%md)%md
    ans %= md

    dpv[0] += dpu[0]
    dpv[1] += dpu[1]+w*dpu[0]%md
    dpv[2] += dpu[2]+2*w*dpu[1]%md+pow(w, 2, md)*dpu[0]%md
    dpv[1] %= md
    dpv[2] %= md

print(ans)