/*

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*/
#include <bits/stdc++.h>
#define ll long long
#define lc(x) ((x) << 1)
#define rc(x) ((x) << 1 | 1)
#define ru(i, l, r) for (int i = (l); i <= (r); i++)
#define rd(i, r, l) for (int i = (r); i >= (l); i--)
#define mid ((l + r) >> 1)
#define pii pair<int, int>
#define mp make_pair
#define fi first
#define se second
#define sz(s) (int)s.size()
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
using namespace std;
#define maxn 100005
mt19937 Rand(chrono::steady_clock::now().time_since_epoch().count());
int read() {
    int x = 0, w = 0; char ch = getchar();
    while(!isdigit(ch)) w |= ch == '-', ch = getchar();
    while(isdigit(ch)) x = x * 10 + ch - '0', ch = getchar();
    return w ? -x : x;
}
int n, q, fa[maxn][22], tdep[maxn];
ll dep[maxn];
vector<pii> G[2][maxn];
void init(int x) {
    ru(i, 1, 20) fa[x][i] = fa[fa[x][i - 1]][i - 1];
    for (auto [V, W]: G[1][x]) if(V ^ fa[x][0]) {
        dep[V] = dep[x] + W, tdep[V] = tdep[x] + 1, fa[V][0] = x, init(V);
    }
}
int dfn[maxn], tot, out[maxn], id[maxn];
ll t[maxn];
void add(int x, ll v) {
    for (; x <= n; x += x & (-x)) t[x] += v;
}
ll que(int x) {
    ll res = 0;
    for (; x; x -= x & (-x)) res += t[x];
    return res;
}
int lca(int x, int y) {
    if(tdep[x] > tdep[y]) swap(x, y);
    rd(i, 20, 0) if(tdep[fa[y][i]] >= tdep[x]) y = fa[y][i];
    if(x == y) return x;
    rd(i, 20, 0) if(fa[x][i] != fa[y][i]) x = fa[x][i], y = fa[y][i];
    return fa[x][0];
}
ll dis(int x, int y) {
    return dep[x] + dep[y] - 2 * dep[lca(x, y)];
}
vector<pii> ask[maxn];
ll ans[maxn];
struct diam {
    int x, y;
}d[maxn];
void pushup(int o) {
    int a[4] = {d[lc(o)].x, d[lc(o)].y, d[rc(o)].x, d[rc(o)].y};
    int x = 0, y = 0; ll z = -1;
    ru(i, 0, 3) ru(j, i + 1, 3) if(a[i] != a[j] && a[i] && a[j]) {
        ll d = dis(id[a[i]], id[a[j]]) + que(a[i]) + que(a[j]);
        //printf("! %d %d %d %d %d %d %lld %lld\n", a[i], a[j], que(a[i]), que(a[j]), id[a[i]], id[a[j]], dis(id[a[i]], id[a[j]]), d);
        if(d > z) z = d, x = a[i], y = a[j];
    }
    d[o] = {x, y};
}
void upd(int x, int l, int r, int a, int b) {
    if(a <= l && r <= b) {
        if(!d[x].x) d[x] = {l, l};
        return;
    }
    if(a <= mid) upd(lc(x), l, mid, a, b);
    if(b > mid) upd(rc(x), mid + 1, r, a, b);
    //printf("ee %d %d\n", l, r);
    pushup(x);
}
void dfs1(int x, int fa, ll d) {
    id[dfn[x] = ++tot] = x;
    add(dfn[x], d), add(dfn[x] + 1, -d);
    upd(1, 1, n, dfn[x], dfn[x]);
    for (auto [V, W]: G[0][x]) if(V ^ fa) dfs1(V, x, d + W);
    out[x] = tot;
}
void dfs2(int x, int fa) {
    //printf("? %d\n", x);
    int a = id[d[1].x], b = id[d[1].y]; //printf("! %d %d %d\n", x, a, b);
    for (auto [v, id]: ask[x]) {
        ans[id] = max(que(a) + dis(v, a), que(b) + dis(v, b));
    }
    for (auto [V, W]: G[0][x]) if(V ^ fa) {
        add(1, W), add(dfn[x], -2 * W), add(out[x] + 1, W);
        dfs2(V, x);
        add(1, -W), add(dfn[x], 2 * W), add(out[x] + 1, -W);
    }
}
int main() {
    n = read(), q = read();
    ru(j, 0, 1) {
        ru(i, 1, n - 1) {
            int u = read(), v = read(), w = read();
            G[j][u].push_back(mp(v, w)), G[j][v].push_back(mp(u, w));
        }
    }
    ru(i, 1, q) {
        int u = read(), v = read();
        ask[u].push_back(mp(v, i));
    }
    init(1);
    dfs1(1, 0, 0);
    dfs2(1, 0);
    ru(i, 1, q) printf("%lld\n", ans[i]);
	return 0;
}