#include <bits/stdc++.h>
#define cs const
#define pb push_back
using namespace std;
using ll = long long ; 
using pi = pair <int, int> ; 
cs int N = 2e3 + 5; 

void cmx(ll & x, ll y) {
    if(x < y) x = y; 
}

int n, q; 
vector <pi> e[N];

ll d[N][N]; 
int fir[N][N];
int lca[N][N];
int LCA(int rt, int u, int v) {
    return lca[rt][u] ^ lca[u][v] ^ lca[rt][v];
}

void dfs(int u, int f, ll * d, int * fir) { 
    for(auto [v, w] : e[u]) if(v != f) {
        d[v] = d[u] + w; 
        if(f) fir[v] = fir[u];
        else fir[v] = v; 
        dfs(v, u, d, fir); 
    }
}
int fa[N];
void dfs1(int u, int f) {
    fa[u] = f; 
    for(auto [v, w] : e[u]) if(v != f) {
        dfs1(v, u);
    }
}
int work(int i, int j) {
    if(lca[i][j]) return lca[i][j];
    if(i == j) return lca[i][j] = i; 
    if(d[1][i] > d[1][j]) {
        return lca[i][j] = work(fa[i], j);
    }
    else {
        return lca[i][j] = work(i, fa[j]);
    }
}

int main() {
    #ifdef zqj
    freopen("1.in","r",stdin);
    #endif
    ios :: sync_with_stdio(0), cin.tie(0);
    cin >> n >> q;
    ll sum = 0; 
    for(int i = 1; i < n; i++) {
        int u, v, w;
        cin >> u >> v >> w; 
        sum += w; 
        e[u].pb({v, w});
        e[v].pb({u, w});
    }
    sum = sum * 2; 

    for(int i = 1; i <= n; i++) {
        dfs(i, 0, d[i], fir[i]); 
    }
    dfs1(1, 0);
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= n; j++)
            work(i, j);
    
    for(int i = 0; i < q; i++) {
        int s, k, t; 
        cin >> s >> k >> t; 
        int p = LCA(s, k, t);
        if(p == t) {
            cout << "impossible\n";
            continue; 
        }
        int q = 0; 
        if(p != k) {
            q = fir[p][k];
        }
        ll ans = 0; 
        for(int j = 1; j <= n; j++) 
            if(!q || (d[s][q] + d[q][j] != d[s][j])) cmx(ans, d[s][j]);
        cout << sum - ans << '\n';
    }

    return 0; 
}