#include <map>
#include <set>
#include <list>
#include <array>
#include <cmath>
#include <deque>
#include <queue>
#include <stack>
#include <tuple>
#include <bitset>
#include <cfloat>
#include <memory>
#include <vector>
#include <random>
#include <string>
#include <cassert>
#include <climits>
#include <cstring>
#include <iomanip>
#include <numeric>
#include <iostream>
#include <algorithm>
#include <functional>
#include <unordered_map>
#include <unordered_set>

using namespace std;

#define rep(i, s, e) for (int i = s; i <= e; ++i)
#define per(i, s, e) for (int i = s; i >= e; --i)
#define file(a) freopen(#a".in", "r", stdin), freopen(#a".out", "w", stdout)
#define pv(a) cout << #a << " = " << a << endl
#define pa(a, l, r) cout << #a " : "; rep(_, l, r) cout << a[_] << " \n"[_ == r]

using i64 = long long;

const int N = 5e5 + 10;
const int M = 20;

int read() {
  int x = 0, f = 1; char c = getchar();
  for (; c < '0' || c > '9'; c = getchar()) if (c == '-') f = -1;
  for (; c >= '0' && c <= '9'; c = getchar()) x = x * 10 + (c - 48);
  return x * f;
}

int n, q, a[N], b[N];
i64 ans[N];
vector <pair <int, int>> qry[N];

namespace t2 {

  vector <pair <int, int>> e[N];
  int p[N], sz[N], dfn[N], dn, st[M][N];
  i64 dep[N];

  void dfs0(int u, int fa) {
    p[u] = fa, sz[u] = 1, dfn[u] = ++dn;
    for (auto [v, w] : e[u]) if (v != fa) {
      dep[v] = dep[u] + w, dfs0(v, u), sz[u] += sz[v];
    }
  }

  int Min(int u, int v) {
    return dep[u] < dep[v] ? u : v;
  }

  int lca(int u, int v) {
    if (u == v) return u;
    u = dfn[u], v = dfn[v];
    if (u > v) swap(u, v);
    int t = log2(v - u);
    return p[Min(st[t][u + 1], st[t][v - (1 << t) + 1])];
  }

  i64 dis(int u, int v) {
    return dep[u] + dep[v] - 2 * dep[lca(u, v)];
  }

  void init() {
    rep(i, 1, n - 1) {
      int u = read(), v = read(), w = read();
      e[u].emplace_back(make_pair(v, w));
      e[v].emplace_back(make_pair(u, w));
    }
    dfs0(1, 0);
    rep(i, 1, n) st[0][dfn[i]] = i;
    rep(j, 1, 19) rep(i, 1, n - (1 << j) + 1) {
      st[j][i] = Min(st[j - 1][i], st[j - 1][i + (1 << (j - 1))]);
    }
  }

}

namespace t1 {

  vector <pair <int, int>> e[N];
  int dfn[N], dn, id[N], sz[N];
  i64 dep[N];

  void dfs0(int u, int fa) {
    dfn[u] = ++dn, id[dn] = u, sz[u] = 1;
    for (auto [v, w] : e[u]) if (v != fa) {
      dep[v] = dep[u] + w, dfs0(v, u), sz[u] += sz[v];
    }
  }

  #define ls (u << 1)
  #define rs (u << 1 | 1)
  #define mid ((l + r) >> 1)

  struct node {
    int u, v;
    i64 x, y, val;
    node(int _u = 0, i64 _x = 0, int _v = 0, i64 _y = 0) {
      u = _u, x = _x, v = _v, y = _y;
      val = t2::dis(u, v) + x + y;
    }
    friend bool operator < (node p, node q) {
      return p.val < q.val;
    }
  } dat[N << 2];
  i64 laz[N << 2];

  void down(int u, i64 k) {
    dat[u].x += k, dat[u].y += k, dat[u].val += 2 * k;
    laz[u] += k;
  }

  void pushdown(int u) {
    if (laz[u]) {
      down(ls, laz[u]), down(rs, laz[u]);
      laz[u] = 0;
    }
  }

  void maintain(int u) {
    dat[u] = max(dat[ls], dat[rs]);
    auto upd = [&](int ul, int ur) {
      node res(ul, laz[ls], ur, laz[rs]);
      if (dat[u] < res) dat[u] = res;
    };
    for (int ul : {dat[ls].u, dat[ls].v}) {
      for (int ur : {dat[rs].u, dat[rs].v}) {
        upd(ul, ur);
      }
    }
  }

  void build(int u, int l, int r) {
    if (l == r) {
      dat[u] = node(id[l], dep[id[l]], id[l], dep[id[l]]);
      laz[u] = dep[id[l]];
      return;
    }
    build(ls, l, mid);
    build(rs, mid + 1, r);
    maintain(u);
  }

  void modify(int ml, int mr, int k, int u, int l, int r) {
    if (mr < l || r < ml) return;
    if (ml <= l && r <= mr) {
      down(u, k);
      return;
    }
    pushdown(u);
    modify(ml, mr, k, ls, l, mid);
    modify(ml, mr, k, rs, mid + 1, r);
    maintain(u);
  }

  int query(int p, int u, int l, int r) {
    if (l == r) {
      return laz[u];
    }
    pushdown(u);
    if (p <= mid) {
      i64 res = query(p, ls, l, mid);
      res = max(res, node(id[p], 0, dat[rs].u, dat[rs].x).val);
      res = max(res, node(id[p], 0, dat[rs].v, dat[rs].y).val);
      // cout << "p, u, l, r, res = " << p << " " << u << " " << l << " " << r << " " << res << endl;
      return res;
    } else {
      i64 res = query(p, rs, mid + 1, r);
      res = max(res, node(id[p], 0, dat[ls].u, dat[ls].x).val);
      res = max(res, node(id[p], 0, dat[ls].v, dat[ls].y).val);
      // cout << "dat[ls].u, dat[ls].x = " << dat[ls].u << " " << dat[ls].x << endl;
      // cout << "dat[ls].v, dat[ls].y = " << dat[ls].v << " " << dat[ls].y << endl;
      // cout << "p, u, l, r, res = " << p << " " << u << " " << l << " " << r << " " << res << endl;
      return res;
    }
  }

  void dfs(int u, int l, int r) {
    if (l == r) {
      cout << laz[u] << " \n"[r == n];
      return;
    }
    pushdown(u);
    dfs(ls, l, mid);
    dfs(rs, mid + 1, r);
  }

  #undef ls
  #undef rs
  #undef mid

  void init() {
    rep(i, 1, n - 1) {
      int u = read(), v = read(), w = read();
      e[u].emplace_back(make_pair(v, w));
      e[v].emplace_back(make_pair(u, w));
    }
    dfs0(1, 0);
  }

  void dfs1(int u, int fa) {
    // pv(u);
    // dfs(1, 1, n);
    for (auto [v, id] : qry[u]) {
      ans[id] = query(dfn[v], 1, 1, n);
    }
    for (auto [v, w] : e[u]) if (v != fa) {
      modify(1, dfn[v] - 1, w, 1, 1, n);
      modify(dfn[v], dfn[v] + sz[v] - 1, -w, 1, 1, n);
      modify(dfn[v] + sz[v], n, w, 1, 1, n);
      dfs1(v, u);
      modify(1, dfn[v] - 1, -w, 1, 1, n);
      modify(dfn[v], dfn[v] + sz[v] - 1, w, 1, 1, n);
      modify(dfn[v] + sz[v], n, 1, -w, 1, n);
    }
  }

  void work() {
    rep(i, 1, q) {
      int u = read(), v = read();
      qry[u].emplace_back(make_pair(v, i));
    }
    build(1, 1, n);
    dfs1(1, 0);
    rep(i, 1, q) {
      printf("%lld\n", ans[i]);
    }
  }

}

int main() {
  n = read(), q = read();
  t1::init();
  t2::init();
  t1::work();
  return 0;
}