func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   const ll MOD = 1e9 + 7;   class SegTree {    private:     const ll NEUT = 0;     vector<ll> seg, tag;     int h = 1;     ll len(int i) { return h >> (31 - __builtin_clz(i)); }     void apply(int i, ll v) {       seg[i] = (seg[i] + v * len(i)) % MOD;       if (i < h) tag[i] = (tag[i] + v) % MOD;     }     void push(int i) {       if (tag[i] == 0) return;       apply(2 * i, tag[i]);       apply(2 * i + 1, tag[i]);       tag[i] = 0;     }     ll combine(ll a, ll b) { return (a + b) % MOD; }     ll recGet(int a, int b, int i, int ia, int ib) {       if (ib <= a || b <= ia) return NEUT;       if (a <= ia && ib <= b) return seg[i];       push(i);       int im = (ia + ib) >> 1;       return combine(recGet(a, b, 2 * i, ia, im),                      recGet(a, b, 2 * i + 1, im, ib));     }     void recApply(int a, int b, ll v, int i, int ia, int ib) {       if (ib <= a || b <= ia) return;       if (a <= ia && ib <= b)         apply(i, v);       else {         push(i);         int im = (ia + ib) >> 1;         recApply(a, b, v, 2 * i, ia, im);         recApply(a, b, v, 2 * i + 1, im, ib);         seg[i] = combine(seg[2 * i], seg[2 * i + 1]);       }     }       public:     SegTree(int n) {       while (h < n) h *= 2;       seg.resize(2 * h, NEUT);       tag.resize(h, 0);     }     ll rangeSum(int a, int b) { return recGet(a, b + 1, 1, 0, h); }     void rangeAdd(int a, int b, ll v) { recApply(a, b + 1, v, 1, 0, h); }   };   class HLD {    private:     vector<int> par, siz, cmp, ind;     void dfs1(int i, vector<vector<int>>& g) {       for (auto& t : g[i]) {         if (t == par[i]) continue;         par[t] = i;         dfs1(t, g);         siz[i] -= siz[t];         if (siz[t] > siz[g[i][0]]) swap(t, g[i][0]);       }       siz[i] *= -1;     }     void dfs2(int i, int& x, const vector<vector<int>>& g) {       ind[i] = x;       ++x;       for (auto t : g[i]) {         if (t == par[i]) continue;         cmp[t] = (x == ind[i] + 1 ? cmp[i] : t);         dfs2(t, x, g);       }     }       public:     HLD(vector<vector<int>> g, int r = 0)         : par(g.size(), -1), siz(g.size(), -1), cmp(g.size(), r), ind(g.size()) {       dfs1(r, g);       int x = 0;       dfs2(r, x, g);     }     const vector<pair<int, int>>& path(int a, int b) const {       static vector<pair<int, int>> res;       res.clear();       for (;; b = par[cmp[b]]) {         if (ind[b] < ind[a]) swap(a, b);         if (ind[cmp[b]] <= ind[a]) {           res.push_back({ind[a], ind[b]});           return res;         }         res.push_back({ind[cmp[b]], ind[b]});       }     }     pair<int, int> subtree(int i) const { return {ind[i], ind[i] + siz[i] - 1}; }     int lca(int a, int b) const {       for (;; b = par[cmp[b]]) {         if (ind[b] < ind[a]) swap(a, b);         if (ind[cmp[b]] <= ind[a]) return a;       }     }     bool deeper(int a, int b) { return siz[a] < siz[b]; }   };   ll modPow(ll a, ll b) {     if (b & 1) return a * modPow(a, b - 1) % MOD;     if (b == 0) return 1;     return modPow(a * a % MOD, b / 2);   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     int n;     cin >> n;     ll colc = 1;     vector<ll> weight(n);     vector<pair<int, int>> evs;     for (int i = 0; i < n; ++i) {       int a, b;       cin >> a >> b;       evs.push_back({a, i + 1});       evs.push_back({b + 1, -(i + 1)});       colc = (colc * (b - a + 1)) % MOD;       weight[i] = modPow(b - a + 1, MOD - 2);     }     sort(evs.begin(), evs.end());     vector<vector<int>> g(n);     for (int i = 0; i < n - 1; ++i) {       int a, b;       cin >> a >> b;       --a;       --b;       g[a].push_back(b);       g[b].push_back(a);     }     HLD hld(g);     ll cur = 0;     ll res = 0;     SegTree above(n), below(n);     int c = 0;     for (int j = 0; j < evs.size(); ++j) {       int nc = evs[j].first;       res = (res + cur * (nc - c)) % MOD;       c = nc;       int i = abs(evs[j].second) - 1;       ll v = (evs[j].second < 0 ? MOD - 1 : 1) * weight[i] % MOD;       vector<pair<int, int>> path = hld.path(i, 0);       int pi = n - 1;       for (auto pr : path) {         cur = (cur + v * below.rangeSum(pr.second + 1, pi)) % MOD;         above.rangeAdd(pr.second + 1, pi, v);         cur = (cur + v * above.rangeSum(pr.first, pr.second)) % MOD;         below.rangeAdd(pr.first, pr.second, v);         pi = pr.first - 1;       }     }     res = (res * colc) % MOD;     if (res < 0) res += MOD;     cout << res <<   n ;   }   