#include <bits/stdc++.h>
#define For(i,a,b) for(int i=a;i<=b;i++)
#define Rev(i,a,b) for(int i=a;i>=b;i--)
#define Fin(file) freopen(file,"r",stdin)
#define Fout(file) freopen(file,"w",stdout)
using namespace std; using ll = long long;
const int N=1e5+5,M=5e5+5; using pii = pair<ll,int>;
int n,Q,head[N],nxt[N*2],to[N*2],edge[N*2],tot,eucnt,lg2[N*2],st[N],ed[N],dfn[N],dfed[N],lis[N],lcnt; vector<pii> cp[N],qry[N]; pii eu[N*2][20]; ll dep[N],ddep[N],ans[M];
inline void add(int x,int y,int z) { nxt[++tot]=head[x]; head[x]=tot; to[tot]=y; edge[tot]=z; }
void dfs2(int u,int pa){
	eu[st[u]=++eucnt][0]=pii(dep[u],u); lis[dfn[u]=++lcnt]=u;
	for(int e=head[u];e;e=nxt[e]){
		int v=to[e]; if(v==pa) continue;
		dep[v]=dep[u]+edge[e]; dfs2(v,u);
		eu[++eucnt][0]=pii(dep[u],u);
	}
	ed[u]=eucnt; dfed[u]=lcnt;
}
int lca(int x,int y){
	if(st[x]>st[y]) swap(x,y);
	int l=st[x],r=ed[y],k=lg2[r-l+1]; int res=min(eu[l][k],eu[r-(1<<k)+1][k]).second; return res;
}
ll dist(int x,int y) { ll res=dep[x]+dep[y]+ddep[x]+ddep[y]-2*dep[lca(x,y)]; /*printf("dist(%d,%d)=%lld\n",x,y,res);*/ return res; }
class STree{
	class FTree{ int n; ll c[N]; public: void init(int _n) { n=_n; };
		inline void poke(int x,int y) { while(x<=n) c[x]+=y,x+=x&(-x); } inline ll peek(int x) { ll r=0; while(x) r+=c[x],x-=x&(-x);; return r; }
	}T;
	int n,a[N][2];
	#define k1 k<<1
	#define k2 k<<1|1
	ll Dist(int x,int y) { return dist(x,y)+T.peek(x)+T.peek(y); }
	void update(int k){
		ll d=0,td=0; For(i,0,1) For(j,0,1) if((td=Dist(a[k1][i],a[k2][j]))>d) d=td,a[k][0]=a[k1][i],a[k][1]=a[k2][j];
	}
	void build(int k,int l,int r){
		if(l==r) return a[k][0]=a[k][1]=lis[l],void();
		int mid=(l+r)>>1; build(k1,l,mid); build(k2,mid+1,r); update(k);
	}
	void modify(int k,int l,int r,int ql,int qr){
		if(ql<=l&&r<=qr) return;
		int mid=(l+r)>>1; if(ql<=mid) modify(k1,l,mid,ql,qr);; if(mid+1<=qr) modify(k2,mid+1,r,ql,qr);; update(k);
	}
public:
	void build(int _n) { n=_n; T.init(n); build(1,1,n); }
	void modify(int l,int r,int w) { T.poke(1,w); T.poke(l,-2*w); T.poke(r+1,2*w); modify(1,1,n,l,r); }
	ll query(int v) { /*printf("query: %d,%d\n",a[1][0],a[1][1]);*/ return max(Dist(v,a[1][0]),Dist(v,a[1][1]))-(ddep[v]+T.peek(dfn[v])); }
}T;
void dfs1(int u,int pa){
	for(auto qr:qry[u]) ans[qr.second]=T.query(qr.first);
	for(auto pr:cp[u]){
		int v=pr.first, e=pr.second; if(v==pa) continue;
		T.modify(dfn[v],dfed[v],e); dfs1(v,u); T.modify(dfn[v],dfed[v],-e);
	}
}
void dfs0(int u,int pa){
	for(auto pr:cp[u]){
		int v=pr.first; if(v!=pa) ddep[v]=ddep[u]+pr.second,dfs0(v,u);
	}
}
int main(){
	cin>>n>>Q;
	For(i,1,n-1) { int x,y,z; cin>>x>>y>>z; cp[x].emplace_back(y,z); cp[y].emplace_back(x,z); }
	For(i,1,n-1) { int x,y,z; cin>>x>>y>>z; add(x,y,z); add(y,x,z); }
	For(i,1,Q) { int x,y; cin>>x>>y; qry[x].emplace_back(y,i); }
	dep[1]=0; dfs2(1,0); lg2[1]=0; For(i,2,eucnt) lg2[i]=lg2[i>>1]+1;
	//~ cout<<dist(1,2)<<'\n';
	For(j,1,lg2[eucnt]) For(i,1,eucnt-(1<<j)+1) eu[i][j]=min(eu[i][j-1],eu[i+(1<<(j-1))][j-1]);
	ddep[1]=0; dfs0(1,0); T.build(n); dfs1(1,0); For(i,1,Q) cout<<ans[i]<<'\n';
	return 0;
}