// >>> TEMPLATES #include using namespace std; using ll = long long; using ld = long double; using i32 = int32_t; using i64 = int64_t; using u32 = uint32_t; using u64 = uint64_t; #define int ll #define double ld #define rep(i,n) for (int i = 0; i < (int)(n); i++) #define rep1(i,n) for (int i = 1; i <= (int)(n); i++) #define repR(i,n) for (int i = (int)(n)-1; i >= 0; i--) #define rep1R(i,n) for (int i = (int)(n); i >= 1; i--) #define loop(i,a,B) for (int i = a; i B; i++) #define loopR(i,a,B) for (int i = a; i B; i--) #define all(x) begin(x), end(x) #define allR(x) rbegin(x), rend(x) #define pb push_back #define eb emplace_back #define mp make_pair #define fst first #define snd second template auto constexpr inf = numeric_limits::max()/2-1; auto constexpr INF32 = inf; auto constexpr INF64 = inf; auto constexpr INF = inf; #ifdef LOCAL #include "debug.hpp" #else #define dump(...) (void)(0) #define say(x) (void)(0) #define debug if (0) #endif template using pque_max = priority_queue; template using pque_min = priority_queue, greater >; template ::value>::type> ostream& operator<<(ostream& os, T const& v) { bool f = true; for (auto const& x : v) os << (f ? "" : " ") << x, f = false; return os; } template ::value>::type> istream& operator>>(istream& is, T &v) { for (auto& x : v) is >> x; return is; } template ostream& operator<<(ostream& os, pair const& p) { return os << "(" << p.first << ", " << p.second << ")"; } template istream& operator>>(istream& is, pair& p) { return is >> p.first >> p.second; } struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup; template struct FixPoint : private F { constexpr FixPoint(F&& f) : F(forward(f)) {} template constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward(x)...); } }; struct MakeFixPoint { template constexpr auto operator|(F&& f) const { return FixPoint(forward(f)); } }; #define MFP MakeFixPoint()| #define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__) template struct vec_impl { using type = vector::type>; template static type make_v(size_t n, U&&... x) { return type(n, vec_impl::make_v(forward(x)...)); } }; template struct vec_impl { using type = T; static type make_v(T const& x = {}) { return x; } }; template using vec = typename vec_impl::type; template auto make_v(Args&&... args) { return vec_impl::make_v(forward(args)...); } template void quit(T const& x) { cout << x << endl; exit(0); } template constexpr bool chmin(T& x, U const& y) { if (x > y) { x = y; return true; } return false; } template constexpr bool chmax(T& x, U const& y) { if (x < y) { x = y; return true; } return false; } template constexpr auto sumof(It b, It e) { return accumulate(b,e,typename iterator_traits::value_type{}); } template int sz(T const& x) { return x.size(); } template int lbd(C const& v, T const& x) { return lower_bound(v.begin(), v.end(), x)-v.begin(); } template int ubd(C const& v, T const& x) { return upper_bound(v.begin(), v.end(), x)-v.begin(); } const int dx[] = { 1,0,-1,0 }; const int dy[] = { 0,1,0,-1 }; constexpr int popcnt(ll x) { return __builtin_popcountll(x); } template struct Random { mt19937_64 mt{random_device{}()}; //mt19937_64 mt{(unsigned)time(0)}; Int a,b; // [a,b] Random(Int a, Int b) : a(a), b(b) {} Int operator()() { return uniform_int_distribution(a,b)(mt); } }; template Int rand(Int a, Int b) { // [a,b] static mt19937_64 mt{random_device{}()}; return uniform_int_distribution(a,b)(mt); } // <<< // >>> reord void reord_impl(vector const&) { } template void reord_impl(vector const& idx, C& v, Args&&... args) { auto t = v; rep (i,v.size()) t[i] = v[idx[i]]; swap(v,t); reord_impl(idx, forward(args)...); } template ()(0,0))> void reord(Comp comp, C& v, Args&&... args) { vector idx(v.size()); iota(idx.begin(), idx.end(), 0); sort(idx.begin(), idx.end(), comp); reord_impl(idx, v, args...); } template void reord(C& v, Args&&... args) { vector idx(v.size()); iota(idx.begin(), idx.end(), 0); sort(idx.begin(), idx.end(), [&](int i, int j) { return v[i] < v[j]; }); reord_impl(idx, v, args...); } template void reordR(C& v, Args&&... args) { vector idx(v.size()); iota(idx.begin(), idx.end(), 0); sort(idx.begin(), idx.end(), [&](int i, int j) { return v[i] > v[j]; }); reord_impl(idx, v, args...); } // <<< // >>> LCA constexpr int dst(int v) { return v; } template constexpr int dst(E const& e) { return e.to; } template struct LCA { vector > const* g; int32_t n,lg,root; vector d; vector > anc; LCA() {} LCA(vector > const* g, int root = 0) : g(g), n(g->size()), root(root), d(n) { lg = 1; while ((1<(n,-1)); dfs(root); rep (i,lg-1) rep (j,n) if (anc[i][j] >= 0) { anc[i+1][j] = anc[i][anc[i][j]]; } } void dfs(int x, int p = -1) { anc[0][x] = p; d[x] = (p == -1 ? 0 : d[p]+1); for (auto const& e : (*g)[x]) if (dst(e) != p) dfs(dst(e),x); } int dep(int a) const { return d[a]; } int operator()(int a, int b) const { return lca(a,b); } int lca(int a, int b) const { if (d[a] > d[b]) swap(a,b); for (int dd = d[b]-d[a], i = 0; dd; dd >>= 1, i++) { if (dd&1) b = anc[i][b]; } if (a == b) return a; for (int i = lg-1; i >= 0; i--) { if (anc[i][a] != anc[i][b]) a = anc[i][a], b = anc[i][b]; } return anc[0][a]; } int dist(int a, int b) const { return d[a] + d[b] - 2*d[lca(a,b)]; } int climb(int v, int dist) const { for (int i = 0; dist && v >= 0; dist >>= 1, i++) { if (dist&1) v = anc[i][v]; } return v; } }; template auto get_lca(vector > const& g, int root = 0) { return LCA(&g,root); } // <<< // >>> segment tree template struct Segtree : Handler { using Value = typename Handler::Value; using Handler::unit; // () -> Value using Handler::merge; // (Value,Value) -> Value vector v; // use v[1..2*cap-1] int cap; // // capacity: power of 2 int n; // original size Segtree() {} template Segtree(T&&... x) { init(forward(x)...); } template ()(0))> void init(int n, F gen) { assert(n >= 0); this->n = n; cap = n; //for (cap = 1; cap < n; cap <<= 1) ;; v.resize(2*cap, unit()); for (int i = 0; i < n; i++) v[cap+i] = gen(i); for (int i = cap-1; i >= 1; i--) v[i] = merge(v[2*i],v[2*i+1]); } void init(int n) { init(n, [&](int) { return unit(); }); } void init(int n, Value const& x) { init(n, [&](int) { return x; }); } void init(vector const& v) { init(v.size(), [&](int i) { return v[i]; }); } int size() const { return n; } void set(int i, Value const& x) { assert(0 <= i); assert(i < size()); i += cap; v[i] = x; while (i > 1) i >>= 1, v[i] = merge(v[2*i],v[2*i+1]); } Value operator[](int i) const { return get(i); } Value get(int i) const { assert(0 <= i); assert(i < size()); return v[cap + i]; } // [l,r) Value get(int l, int r) const { assert(0 <= l); assert(l <= r); assert(r <= size()); Value x = unit(), y = unit(); for (l += cap, r += cap; l < r; l >>= 1, r >>= 1) { if (l&1) x = merge(x, v[l++]); if (r&1) y = merge(v[--r], y); } return merge(x,y); } vector dat() const { vector ret(size()); for (int i = 0; i < size(); i++) ret[i] = get(i); return ret; } }; // <<< struct RangeXor { using Value = u64; constexpr static Value unit() { return 0; } constexpr static Value merge(Value x, Value y) { return x^y; } }; struct edge { int to,w; }; int32_t main() { int n; cin >> n; vector> g(n); vector a(n-1),b(n-1),w(n-1); rep (i,n-1) { cin >> a[i] >> b[i] >> w[i], --a[i],--b[i]; g[a[i]].pb({b[i],w[i]}); g[b[i]].pb({a[i],w[i]}); } reord(w,a,b); dump(a); dump(b); dump(w); auto lca = get_lca(g); vector dep(n), in(n), out(n); int time = 0; def (dfs, int x, int p, int d) -> void { dep[x] = d; in[x] = time; for (auto e : g[x]) { if (e.to == p) continue; time++; dfs(e.to,x,d+e.w); time++; } out[x] = time+1; }; dfs(0,-1,0); dump(dep); dump(in); dump(out); int q; cin >> q; vector x(q),y(q); rep (i,q) cin >> x[i] >> y[i], --x[i],--y[i]; vector l(q,0),r(q,1e10); while (true) { // dump(l,r); static map> z; z.clear(); rep (i,q) { if (l[i]+1 < r[i]) { int mid = (l[i]+r[i])/2; z[mid].eb(i); } } if (z.empty()) break; static Segtree seg(2*n); fill(all(seg.v),0); auto add = [&](int x, u64 val) { seg.set(in[x], seg[in[x]]^val); seg.set(out[x], seg[out[x]]^val); }; int idx = 0; for (auto const& [mid,v] : z) { while (idx < n-1 && w[idx] <= mid) { auto val = rand(0ull,-1ull); add(a[idx], val); add(b[idx], val); idx++; } for (int j : v) { u64 sum = 0; sum ^= seg.get(0,in[x[j]]+1); sum ^= seg.get(0,in[y[j]]+1); sum ^= seg.get(in[lca(x[j],y[j])]); (sum > 0 ? r[j] : l[j]) = mid; } } } // dump(l); // dump(r); rep (i,q) { if (r[i] == int(1e10)) { cout << -1 << "\n"; } else { int mi = r[i]; int len = dep[x[i]] + dep[y[i]] - 2*dep[lca(x[i],y[i])]; // dump(i,x[i],y[i],mi,len); cout << len + mi*2 << "\n"; } } }