#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1e6+10;
int n,q;
vector<pair<int,int> >A[N];
vector<pair<int,int> >B[N];
vector<pair<int,int> >b[N];
int ans[N*5];

int A_dfn[N],B_dfn[N];
int dfn;
int e[N<<1],tot;
int ST[N<<1][30];
int p[N];
int rdis[N];//B 树到根的距离
int a[N],to_a[N];
int mn[N],mx[N];//A 树的子树区段
void pdfs(int u,int fa){
    B_dfn[u] = ++dfn;
    e[++tot] = B_dfn[u];
    p[B_dfn[u]] = tot;
    for(auto v:B[u]){
        if(v.first == fa)continue;
        rdis[v.first] = rdis[u] + v.second;
        pdfs(v.first,u);
        e[++tot] = B_dfn[u];
    }
}
void init(){
    for(int i=1;i<=tot;i++)ST[i][0] = e[i];
    for(int i=1;i<20;i++){
        for(int j=1;j<=tot;j++){
            ST[j][i] = ST[j][i-1];
            if(j+(1<<(i-1)) <= tot)ST[j][i] = min(ST[j][i-1],ST[j+(1<<(i-1))][i-1]);
        }
    }
}
int log(int len){return 63 - __builtin_clzll(len*1ull);}
int get_dis(int u,int v){
    if(u==v)return 0;
    //get lca
    int ret = 0;
    if(p[B_dfn[u]] > p[B_dfn[v]])swap(u,v);
    int k = log(p[B_dfn[v]] - p[B_dfn[u]] + 1);
    assert(k<20);
    int lca = min(ST[p[B_dfn[u]]][k],ST[p[B_dfn[v]] - (1<<k) + 1][k]);
    //get dis
    ret = rdis[u] + rdis[v] - 2*rdis[lca];
    return ret;
}

void dfs(int u,int fa){
    A_dfn[u] = ++dfn;
    to_a[dfn] = u;
    mn[u] = mx[u] = dfn;
    for(auto v:A[u]){
        if(v.first == fa)continue;
        a[v.first] = a[u] + v.second;
        dfs(v.first,u);
        mx[u] = max(mx[u],mx[v.first]);
    }
}

int p1[N<<2],p2[N<<2],w1[N<<2],w2[N<<2],lz[N<<2];

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

void pushup(int x){
    int _p[4] = {p1[ls],p2[ls],p1[rs],p2[rs]};
    int _w[4] = {w1[ls],w2[ls],w1[rs],w2[rs]};
    int dis = 0,rp1 = 0,rp2 = 0,rw1 = 0,rw2 = 0;
    for(int i=0;i<3;i++){
        for(int j=i+1;j<4;j++){
            if(_p[i] == _p[j]){
                if(dis < _w[i]){
                    dis = _w[i];
                    rp1 = _p[i];rp2 = _p[j];
                    rw1 = _w[i];rw2 = _w[j];
                }
            }else{
                int d = get_dis(_p[i],_p[j]);
                if(dis < d + _w[i] + _w[j]){
                    dis = d + _w[i] + _w[j];
                    rp1 = _p[i];rp2 = _p[j];
                    rw1 = _w[i];rw2 = _w[j];
                }
            }
        }
    }
    p1[x] = rp1;p2[x] = rp2;
    w1[x] = rw1;w2[x] = rw2;
}
void pushdown(int x){
    int lazy = lz[x];
    lz[x] = 0;
    w1[ls] += lazy;w2[ls] += lazy;lz[ls] += lazy;
    w1[rs] += lazy;w2[rs] += lazy;lz[rs] += lazy;
}
void build(int x,int l,int r){
    if(l==r){
        p1[x] = p2[x] = to_a[l];
        w1[x] = w2[x] = a[to_a[l]];
        return ;
    }
    build(ls,l,mid);build(rs,mid+1,r);
    pushup(x);
}
void mdf(int x,int l,int r,int L,int R,int v){
    if(L<=l && r<=R){
        w1[x] += v;w2[x] += v;
        lz[x] += v;
        return ;
    }
    pushdown(x);
    if(L<=mid)mdf(ls,l,mid,L,R,v);
    if(r>mid)mdf(rs,mid+1,r,L,R,v);
    pushup(x);
}
void hg(int u,int fa){
    //statistics
    for(auto i:b[u]){
        ans[i.second] = max(get_dis(i.first,p1[1])+w1[1],get_dis(i.first,p2[1])+w2[1]);
    }
    for(auto v:A[u]){
        if(v.first==fa)continue;
        //in
        mdf(1,1,n,1,n,v.second);
        mdf(1,1,n,mn[v.first],mx[u],-2*v.second);
        hg(v.first,u);
        //out
        mdf(1,1,n,mn[v.first],mx[u],2*v.second);
        mdf(1,1,n,1,n,-v.second);
    }
}

void solve(){
    cin>>n>>q;
    for(int i=1,u,v,w;i<n;i++){
        cin>>u>>v>>w;
        A[u].push_back({v,w});
        A[v].push_back({u,w});
    }
    for(int i=1,u,v,w;i<n;i++){
        cin>>u>>v>>w;
        B[u].push_back({v,w});
        B[v].push_back({u,w});
    }
    for(int i=1,ta,tb;i<=q;i++){
        cin>>ta>>tb;
        b[ta].push_back({tb,i});
    }
    //预处理B树的树上距离
    pdfs(1,0);dfn=0;
    init();
    //线段树
    //求出根节点答案 build
    dfs(1,0);
    build(1,1,n);
    //换根

    hg(1,0);

    // cout<<p1[1]<<' '<<p2[1]<<' '<<w1[1]<<' '<<w2[1]<<endl;
    // cout<<get_dis(p1[1],p2[1]) + w1[1] + w2[1]<<endl;

    //输出
    for(int i=1;i<=q;i++)cout<<ans[i]<<'\n';
}
signed main(){
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    int aqx = 1;
    //cin>>aqx;
    while(aqx--)solve();
    return 0;
}