#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 4005;
const ll LLINF = 0x3f3f3f3f3f3f3f3f;
 
vector <pair <int,int> > G[N];
int n,Q;
 
int dfc = 0,dfn[N],siz[N];
ll dep[N];
void init_dfs(int u,int f){
    dfn[u] = ++ dfc;
    siz[u] = 1;
    for(auto [v,w] : G[u]){
        if(v == f) continue;
        dep[v] = dep[u] + w;
        init_dfs(v,u);
        siz[u] += siz[v];
    }
}
 
int k,t;
ll dt,dk;
ll ans,sumw2 = 0;
void dfs(int u,int f){
    if(dfn[u] <= dfn[t] && dfn[t] <= dfn[u] + siz[u] - 1) dt = dep[u];
    if(dfn[u] <= dfn[k] && dfn[k] <= dfn[u] + siz[u] - 1) dk = dep[u];
    int is_leaf = 1;
    for(auto [v,w] : G[u]){
        if(v == f) continue;
        dfs(v,u);
        if(dfn[u] <= dfn[t] && dfn[t] <= dfn[u] + siz[u] - 1) dt = dep[u];
        if(dfn[u] <= dfn[k] && dfn[k] <= dfn[u] + siz[u] - 1) dk = dep[u];
        is_leaf = 0;
    }
    if(is_leaf){
        ans = min(ans,sumw2 - dep[u] + 2 * max(0ll,dk - dt));
    }
}
 
void solve(){
    cin >> n >> Q;
    for(int u,v,w,i = 1;i < n;i ++){
        cin >> u >> v >> w;
        G[u].push_back({v,w});
        G[v].push_back({u,w});
        sumw2 += 2ll * w;
    }
    for(int s,i = 1;i <= Q;i ++){
        cin >> s >> k >> t;
        dfc = 0; dep[s] = 0;
        init_dfs(s,0);
        ans = LLINF;
        dfs(s,0);
        if(dfn[t] <= dfn[k] && dfn[k] <= dfn[t] + siz[t] - 1) cout << "impossible\n";
        else cout << ans << '\n';
    }
}
 
int main(){
    ios::sync_with_stdio(false);
    solve();
    return 0;
}