#include <bits/stdc++.h>
template<class T> inline bool chmin(T&a, T b){if(a > b){a = b; return true;}else{return false;}}
template<class T> inline bool chmax(T&a, T b){if(a < b){a = b; return true;}else{return false;}}
#define ll long long
#define double long double
#define rep(i,n) for(int i=0;i<(n);i++)
#define REP(i,n) for(int i=1;i<=(n);i++)
#define mod (ll)(1e9+7)
#define inf (ll)(3e18+7)
#define eps (double)(1e-9)
#define pi (double) acos(-1)
#define P pair<int,int>
#define PiP pair<int,pair<int,int>>
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
using namespace std;

struct edge{
    ll to, cost;
};

ll now = 0;
void dfs(const vector<vector<edge>> &G, int v, int p, int d){
    int cnt = 0;
    for(auto nv : G[v]){
        if(nv.to == p)continue;
        dfs(G, nv.to, v, d + nv.cost);
        cnt++;
    }
    if(cnt == 0)now += d;
}

ll solve(int n, int k, vector<int> a, vector<int> b, vector<int> c){
    ll ret = 0;
    for(int bit = 0; bit < (1LL<<(n-1)); bit++){
        ll sum = 0;
        vector<vector<edge>> G(n);
        rep(i, n-1)if(bit & (1<<i))sum += c[i];
        rep(i, n-1){
            if(bit & (1<<i)){
                G[a[i]].push_back({b[i], c[i]*2});
                G[b[i]].push_back({a[i], c[i]*2});
            }else{
                G[a[i]].push_back({b[i], c[i]});
                G[b[i]].push_back({a[i], c[i]});
            }
        }
        if(sum > k)continue;
        dfs(G, 0, -1, 0);
        chmax(ret, now);
        now = 0;
    }
    return ret;
}

int main() {
    int n, k;
    cin >> n >> k;
    vector<int> a(n-1), b(n-1), c(n-1);
    rep(i, n-1){
        cin >> a[i] >> b[i] >> c[i];
        a[i]--;
        b[i]--;
    }
    if(n >= 21){
        cout << -1 << endl;
        return 0;
    }
    cout << solve(n, k, a, b, c);
}