#pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include<bits/stdc++.h>
// #include<atcoder/all>
#define FR(i,n) for(int i=0;i<n;++i)
#define eb emplace_back
#define st first
#define nd second
#define x1 fxxkcjb
#define y1 fxxkyzc
#define x2 fxxkzzy
#define y2 fxxknitit
using namespace std;
namespace R=ranges;
template<typename T>
using func=function<T>;
template<typename T>
using vec=vector<T>;
using ll=long long;
using ld=long double;
using i128=__int128;
using pll=pair<ll,ll>;
const int mod=998244353;
void sol(){
    int n,q;cin>>n>>q;
    vector g(n,vector<pll>());
    
    int total=0;
    FR(i,n-1){
        int x,y,z;cin>>x>>y>>z;--x,--y;
        g[x].eb(y,z),g[y].eb(x,z);
        total+=2*z;
    }
    vector f(11,vector<int>(n,-1));
    vector<ll>DIS(n),dep(n);
    func<void(int)>build=[&](int x){
        for(int i=1;i<11;++i)f[i][x]=f[i-1][x]==-1?-1:f[i-1][f[i-1][x]];
        for(auto[y,z]:g[x])if(y!=f[0][x]){
            f[0][y]=x;
            DIS[y]=DIS[x]+z;
            dep[y]=dep[x]+1;
            build(y);
        }
    };
    DIS[0]=dep[0]=0;
    build(0);
    auto lca=[&](int x,int y){
        if(dep[x]<dep[y])swap(x,y);
        for(int i=10;~i;--i)if(f[i][x]!=-1&&dep[f[i][x]]>=dep[y])x=f[i][x];
        if(x==y)return x;
        for(int i=10;~i;--i)if(f[i][x]!=f[i][y])x=f[i][x],y=f[i][y];
        return f[0][x];
    };
    auto dis=[&](pll u){
        return DIS[u.st]+DIS[u.nd]-2*DIS[lca(u.st,u.nd)];
    };
    auto upd=[&](pll&u,pll v){
        if(dis(u)<dis(v))u=v;
    };
    auto merge=[&](pll u,pll v){
        auto[a,b]=u;
        auto[c,d]=v;
        pll ret=u;
        upd(ret,v);
        upd(ret,{a,c});
        upd(ret,{a,d});
        upd(ret,{b,c});
        upd(ret,{b,d});
        // too slow?
        return ret;
    };
    vector<pll>ind(n),otd(n);
    func<void(int)>dfs=[&](int x){
        ind[x]={x,x};
        for(auto[y,z]:g[x])if(y!=f[0][x]){
            dfs(y);
            ind[x]=merge(ind[x],ind[y]);
        }
    };
    dfs(0);
    func<void(int)>dfs2=[&](int x){
        pll tmp=merge(otd[x],{x,x});
        vector<int>c;
        for(auto[y,z]:g[x])if(y!=f[0][x])c.eb(y);
        vector<pll>tmps(c.size());
        FR(i,c.size())tmps[i]=tmp,tmp=merge(tmp,ind[c[i]]);
        tmp=merge(otd[x],{x,x});
        for(int i=c.size()-1;~i;--i){
            otd[c[i]]=merge(tmp,tmps[i]);
            dfs2(c[i]);
            tmp=merge(tmp,ind[c[i]]);
        }
    };
    auto mxdis=[&](int x,pll u){return max(dis({x,u.st}),dis({x,u.nd}));};
    otd[0]={0,0};//not correct but should work
    dfs2(0);
    FR(tim,q){
        int s,k,t;cin>>s>>k>>t;--s,--k,--t;
        if(dis({s,k})==dis({s,t})+dis({t,k})){ //trap is on s->k
            cout<<"impossible\n";
            continue;
        }
        if(dis({s,t})==dis({s,k})+dis({k,t})){ //key is on s->t
            cout<<total-mxdis(s,ind[0])<<"\n";
            continue;
        }
        int trip;
        {
            trip=lca(s,k);
            int tmp=lca(s,t);
            if(dep[tmp]<dep[trip])trip=tmp;
            tmp=lca(k,t);
            if(dep[tmp]<dep[trip])trip=tmp;
        }
        assert(trip!=k);
        pll sside,kside;
        if(lca(trip,k)==trip){
            //k is inside trip tree
            int ptr=k;
            for(int i=10;~i;--i)if(f[i][ptr]!=-1&&dep[f[i][ptr]]>dep[trip])ptr=f[i][ptr];
            assert(f[0][ptr]==trip);
            sside=otd[ptr];
            kside=ind[ptr];
        }else{
            //k is outside trip
            sside=ind[trip];
            kside=otd[trip];
        }
        int mx1=mxdis(s,sside),mx2=mxdis(k,kside)-dis({k,trip})+dis({s,trip});
        cout<<total-max(mx1,mx2)<<"\n";
    }
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    sol();
    return 0;
}
/*
5 4
1 2 3
1 3 1
3 4 4
3 5 2
1 2 4
1 4 2
5 2 1
4 3 1

*/