#include <bits/stdc++.h>

using namespace std;

#define ll long long

typedef pair<int, ll> P;
#define fi first
#define se second

const int N = 1e5 + 5;
const int M = 5e5 + 5;

int n, m;
vector <P> q[N];
int ans[M];

struct Tree
{
	vector <P> G[N];
	int fa[N], siz[N], son[N], dep[N];
	ll dis[N];
	int top[N], tim, dfn[N], id[N];
	
	void dfs1(int u, int p)
	{
		fa[u] = p, siz[u] = 1, dep[u] = dep[p] + 1;
		for(auto v : G[u])
		{
			if(v.fi == p) continue;
			dis[v.fi] = dis[u] + v.se;
			dfs1(v.fi, u); siz[u] += siz[v.fi];
			if(siz[v.fi] > siz[son[u]]) son[u] = v.fi;
		}
		return;
	}
	
	void dfs2(int u, int tp)
	{
		top[u] = tp, dfn[u] = ++tim, id[tim] = u;
		if(son[u]) dfs2(son[u], tp);
		for(auto v : G[u])
			if(v.fi != fa[u] && v.fi != son[u]) dfs2(v.fi, v.fi);
		return;
	}
	
	int LCA(int x, int y)
	{
		while(top[x] != top[y])
		{
			if(dep[top[x]] < dep[top[y]]) swap(x, y);
			x = fa[top[x]];
		}
		return dep[x] < dep[y] ? x : y;
	}
	
	ll Dis(int x, int y)
	{
		if(!x || !y) return 0;
		return dis[x] + dis[y] - dis[LCA(x, y)] * 2;
	}
} A, B;

struct Path
{
	P s, t; ll dis;
	Path(P _s = {0, 0}, P _t = {0, 0}) {s = _s, t = _t, dis = B.Dis(s.fi, t.fi) + s.se + t.se;}
	bool operator < (const Path &rhs) const {return dis < rhs.dis;}
    friend Path operator + (Path x, Path y)
    {
        Path z = max(x, y);
        z = max({z, Path(x.s, y.s), Path(x.s, y.t)});
        z = max({z, Path(x.t, y.s), Path(x.t, y.t)});
        return z;
    }
};

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

Path t[N << 2];
ll tag[N << 2];

void pushtag(int rt, ll v)
{
    t[rt].s.se += v, t[rt].t.se += v;
    if(t[rt].t.fi) t[rt].dis += 2 * v;
	tag[rt] += v;
}

void pushdown(int rt)
{
	if(!tag[rt]) return;
	pushtag(ls, tag[rt]), pushtag(rs, tag[rt]);
	tag[rt] = 0;
}

void build(int l, int r, int rt)
{
	if(l == r) return t[rt] = Path({A.id[l], B.dis[A.id[l]]}, {0, 0}), void();
	build(l, mid, ls), build(mid + 1, r, rs);
    t[rt] = t[ls] + t[rs];
}

void upd(int L, int R, int v, int l = 1, int r = n, int rt = 1)
{
	if(L > R || l > R || r < L) return;
	if(L <= l && r <= R) return pushtag(rt, v);
	pushdown(rt);
	upd(L, R, v, l, mid, ls), upd(L, R, v, mid + 1, r, rs);
    t[rt] = t[ls] + t[rs];
}

void update(int l, int r, int v)
{
    upd(1, n, v), upd(l, r, -2 * v);
}

int qry(int x)
{
    Path p = t[1];
    return max(B.Dis(x, p.s.fi) + p.s.se, B.Dis(x, p.t.fi) + p.t.se);
}

void dfs3(int u)
{
	for(auto p : q[u]) ans[p.se] = qry(p.fi);
	for(auto v : A.G[u])
	{
		if(v.fi == A.fa[u]) continue;
		update(A.dfn[v.fi], A.dfn[v.fi] + A.siz[v.fi] - 1, v.se);
		dfs3(v.fi);
		update(A.dfn[v.fi], A.dfn[v.fi] + A.siz[v.fi] + 1, -v.se);
	}
	return;
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr), cout.tie(nullptr);
	
	cin >> n >> m;
	for(int i = 1, u, v, w; i < n; i++)
		cin >> u >> v >> w, A.G[u].push_back({v, w}), A.G[v].push_back({u, w});
	for(int i = 1, u, v, w; i < n; i++)
		cin >> u >> v >> w, B.G[u].push_back({v, w}), B.G[v].push_back({u, w});
	for(int i = 1, a, b; i <= m; i++)
		cin >> a >> b, q[a].push_back({b, i});

	A.dfs1(1, 0), A.dfs2(1, 1);
	B.dfs1(1, 0), B.dfs2(1, 1);
	build(1, n, 1); dfs3(1);

	for(int i = 1; i <= m; i++) cout << ans[i] << '\n';
	return 0;
}