#include using namespace std; typedef long long ll; #define pb(x) push_back(x) #define mp(a, b) make_pair(a, b) #define all(x) x.begin(), x.end() #define rall(x) x.rbegin(), x.rend() #define lscan(x) scanf("%I64d", &x) #define lprint(x) printf("%I64d", x) const int mod = 1000000007; ll gcd(ll a, ll b) { ll c = a % b; while (c != 0) { a = b; b = c; c = a % b; } return b; } long long extGCD(long long a, long long b, long long &x, long long &y) { if (b == 0) { x = 1; y = 0; return a; } long long d = extGCD(b, a % b, y, x); y -= a / b * x; return d; } struct UnionFind { vector data; UnionFind(int sz) { data.assign(sz, -1); } bool unite(int x, int y) { x = find(x), y = find(y); if (x == y) return (false); if (data[x] > data[y]) swap(x, y); data[x] += data[y]; data[y] = x; return (true); } int find(int k) { if (data[k] < 0) return (k); return (data[k] = find(data[k])); } ll size(int k) { return (-data[find(k)]); } }; ll M = 1000000007; vector fac(2000011); //n!(mod M) vector ifac(2000011); //k!^{M-2} (mod M) ll mpow(ll x, ll n) { ll ans = 1; while (n != 0) { if (n & 1) ans = ans * x % M; x = x * x % M; n = n >> 1; } return ans; } ll mpow2(ll x, ll n, ll mod) { ll ans = 1; while (n != 0) { if (n & 1) ans = ans * x % mod; x = x * x % mod; n = n >> 1; } return ans; } void setcomb() { fac[0] = 1; ifac[0] = 1; for (ll i = 0; i < 2000010; i++) { fac[i + 1] = fac[i] * (i + 1) % M; // n!(mod M) } ifac[2000010] = mpow(fac[2000010], M - 2); for (ll i = 2000010; i > 0; i--) { ifac[i - 1] = ifac[i] * i % M; } } ll comb(ll a, ll b) { if (a == 0 && b == 0) return 1; if (a < b || a < 0) return 0; ll tmp = ifac[a - b] * ifac[b] % M; return tmp * fac[a] % M; } ll perm(ll a, ll b) { if (a == 0 && b == 0) return 1; if (a < b || a < 0) return 0; return fac[a] * ifac[a - b] % M; } long long modinv(long long a) { long long b = M, u = 1, v = 0; while (b) { long long t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } u %= M; if (u < 0) u += M; return u; } ll modinv2(ll a, ll mod) { ll b = mod, u = 1, v = 0; while (b) { ll t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } u %= mod; if (u < 0) u += mod; return u; } template struct ModInt { int x; ModInt() : x(0) {} ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} ModInt &operator+=(const ModInt &p) { if ((x += p.x) >= mod) x -= mod; return *this; } ModInt &operator-=(const ModInt &p) { if ((x += mod - p.x) >= mod) x -= mod; return *this; } ModInt &operator*=(const ModInt &p) { x = (int)(1LL * x * p.x % mod); return *this; } ModInt &operator/=(const ModInt &p) { *this *= p.inverse(); return *this; } ModInt operator-() const { return ModInt(-x); } ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; } ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; } ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; } ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; } bool operator==(const ModInt &p) const { return x == p.x; } bool operator!=(const ModInt &p) const { return x != p.x; } ModInt inverse() const { int a = x, b = mod, u = 1, v = 0, t; while (b > 0) { t = a / b; swap(a -= t * b, b); swap(u -= t * v, v); } return ModInt(u); } ModInt pow(int64_t n) const { ModInt ret(1), mul(x); while (n > 0) { if (n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; } friend istream &operator>>(istream &is, ModInt &a) { int64_t t; is >> t; a = ModInt(t); return (is); } static int get_mod() { return mod; } }; using mint = ModInt; vector> mul(vector> a, vector> b, int n) { int i, j, k, t; vector> c(n); for (i = 0; i < n; i++) { for (j = 0; j < n; j++) { t = 0; for (k = 0; k < n; k++) t = (t + a[i][k] * b[k][j] % M) % M; c[i].push_back(t); } } return c; } template struct SegmentTree { using F = function; int sz; vector seg; const F f; const Monoid M1; SegmentTree(int n, const F f, const Monoid &M1) : f(f), M1(M1) { sz = 1; while (sz < n) sz <<= 1; seg.assign(2 * sz, M1); } void set(int k, const Monoid &x) { seg[k + sz] = x; } void build() { for (int k = sz - 1; k > 0; k--) { seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]); } } void update(int k, const Monoid &x) { k += sz; seg[k] = x; while (k >>= 1) { seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]); } } Monoid query(int a, int b) { Monoid L = M1, R = M1; for (a += sz, b += sz; a < b; a >>= 1, b >>= 1) { if (a & 1) L = f(L, seg[a++]); if (b & 1) R = f(seg[--b], R); } return f(L, R); } Monoid operator[](const int &k) const { return seg[k + sz]; } template int find_subtree(int a, const C &check, Monoid &M, bool type) { while (a < sz) { Monoid nxt = type ? f(seg[2 * a + type], M) : f(M, seg[2 * a + type]); if (check(nxt)) a = 2 * a + type; else M = nxt, a = 2 * a + 1 - type; } return a - sz; } template int find_first(int a, const C &check) { Monoid L = M1; if (a <= 0) { if (check(f(L, seg[1]))) return find_subtree(1, check, L, false); return -1; } int b = sz; for (a += sz, b += sz; a < b; a >>= 1, b >>= 1) { if (a & 1) { Monoid nxt = f(L, seg[a]); if (check(nxt)) return find_subtree(a, check, L, false); L = nxt; ++a; } } return -1; } template int find_last(int b, const C &check) { Monoid R = M1; if (b >= sz) { if (check(f(seg[1], R))) return find_subtree(1, check, R, true); return -1; } int a = sz; for (b += sz; a < b; a >>= 1, b >>= 1) { if (b & 1) { Monoid nxt = f(seg[--b], R); if (check(nxt)) return find_subtree(b, check, R, true); R = nxt; } } return -1; } }; template struct RollingHash { vector hashed, power; inline unsigned mul(unsigned a, unsigned b) const { unsigned long long x = (unsigned long long)a * b; unsigned xh = (unsigned)(x >> 32), xl = (unsigned)x, d, m; asm("divl %4; \n\t" : "=a"(d), "=d"(m) : "d"(xh), "a"(xl), "r"(mod)); return m; } RollingHash(const string &s, unsigned base = 10007) { int sz = (int)s.size(); hashed.assign(sz + 1, 0); power.assign(sz + 1, 0); power[0] = 1; for (int i = 0; i < sz; i++) { power[i + 1] = mul(power[i], base); hashed[i + 1] = mul(hashed[i], base) + s[i]; if (hashed[i + 1] >= mod) hashed[i + 1] -= mod; } } unsigned get(int l, int r) const { unsigned ret = hashed[r] + mod - mul(hashed[l], power[r - l]); if (ret >= mod) ret -= mod; return ret; } unsigned connect(unsigned h1, int h2, int h2len) const { unsigned ret = mul(h1, power[h2len]) + h2; if (ret >= mod) ret -= mod; return ret; } int LCP(const RollingHash &b, int l1, int r1, int l2, int r2) { int len = min(r1 - l1, r2 - l2); int low = -1, high = len + 1; while (high - low > 1) { int mid = (low + high) / 2; if (get(l1, l1 + mid) == b.get(l2, l2 + mid)) low = mid; else high = mid; } return (low); } }; using RH = RollingHash<1000000007>; template struct edge { int src, to; T cost; edge(int to, T cost) : src(-1), to(to), cost(cost) {} edge(int src, int to, T cost) : src(src), to(to), cost(cost) {} edge &operator=(const int &x) { to = x; return *this; } operator int() const { return to; } }; template using Edges = vector>; template using WeightedGraph = vector>; using UnWeightedGraph = vector>; template using Matrix = vector>; template struct DoublingLowestCommonAncestor { const int LOG; vector dep; const G &g; vector> table; DoublingLowestCommonAncestor(const G &g) : g(g), dep(g.size()), LOG(32 - __builtin_clz(g.size())) { table.assign(LOG, vector(g.size(), -1)); } void dfs(int idx, int par, int d) { table[0][idx] = par; dep[idx] = d; for (auto &to : g[idx]) { if (to != par) dfs(to, idx, d + 1); } } void build() { dfs(0, -1, 0); for (int k = 0; k + 1 < LOG; k++) { for (int i = 0; i < table[k].size(); i++) { if (table[k][i] == -1) table[k + 1][i] = -1; else table[k + 1][i] = table[k][table[k][i]]; } } } int query(int u, int v) { if (dep[u] > dep[v]) swap(u, v); for (int i = LOG - 1; i >= 0; i--) { if (((dep[v] - dep[u]) >> i) & 1) v = table[i][v]; } if (u == v) return u; for (int i = LOG - 1; i >= 0; i--) { if (table[i][u] != table[i][v]) { u = table[i][u]; v = table[i][v]; } } return table[0][u]; } }; vector li[1111111]; mint ans = 0; void dfs(ll now, ll d, mint sum){ sum += d; ans += sum; for(auto &e:li[now]) dfs(e, d + 1, sum); } int main() { int n, i, f[1111111] = {}, a, b; cin>>n; for (i = 0; i < n - 1;i++){ cin>>a>>b; a--; b--; li[a].pb(b); f[b]++; } for (i = 0; i < n;i++) if(!f[i]) dfs(i, 0, 0); cout << ans << endl; }