//Utkarsh.25dec
#include <bits/stdc++.h>
#define ll long long int
#define pb push_back
#define mp make_pair
#define mod 1000000007
#define vl vector <ll>
#define all(c) (c).begin(),(c).end()
using namespace std;
ll power(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll modInverse(ll a){return power(a,mod-2);}
const int N=500023;
bool vis[N];
vector <pair<int,int>> adj[N];
vector <int> adjnew[N];
int subtree[N];
int alreadyaffected=0;
long long readInt(long long l,long long r,char endd){
    long long x=0;
    int cnt=0;
    int fi=-1;
    bool is_neg=false;
    while(true){
        char g=getchar();
        if(g=='-'){
            assert(fi==-1);
            is_neg=true;
            continue;
        }
        if('0'<=g && g<='9'){
            x*=10;
            x+=g-'0';
            if(cnt==0){
                fi=g-'0';
            }
            cnt++;
            assert(fi!=0 || cnt==1);
            assert(fi!=0 || is_neg==false);

            assert(!(cnt>19 || ( cnt==19 && fi>1) ));
        } else if(g==endd){
            if(is_neg){
                x= -x;
            }

            if(!(l <= x && x <= r))
            {
                cerr << l << ' ' << r << ' ' << x << '\n';
                assert(1 == 0);
            }

            return x;
        } else {
            assert(false);
        }
    }
}
string readString(int l,int r,char endd){
    string ret="";
    int cnt=0;
    while(true){
        char g=getchar();
        assert(g!=-1);
        if(g==endd){
            break;
        }
        cnt++;
        ret+=g;
    }
    assert(l<=cnt && cnt<=r);
    return ret;
}
long long readIntSp(long long l,long long r){
    return readInt(l,r,' ');
}
long long readIntLn(long long l,long long r){
    return readInt(l,r,'\n');
}
string readStringLn(int l,int r){
    return readString(l,r,'\n');
}
string readStringSp(int l,int r){
    return readString(l,r,' ');
}
void checktree(int curr)
{
    vis[curr]=1;
    for(auto it:adj[curr])
    {
        if(vis[it.first]!=0)
            continue;
        checktree(it.first);
    }
}
void dfs(int curr)
{
    vis[curr]=1;
    alreadyaffected++;
    for(auto it:adj[curr])
    {
        if(vis[it.first]==1)
            continue;
        if(it.second==1)
            continue;
        dfs(it.first);
    }
}
void subtreesz(int curr)
{
    vis[curr]=1;
    subtree[curr]=1;
    for(auto it:adjnew[curr])
    {
        if(vis[it])
            continue;
        subtreesz(it);
        subtree[curr]+=subtree[it];
    }
}
void solve()
{
    int n,k;
    n=readInt(1,200000,' ');
    k=readInt(1,n,'\n');
    alreadyaffected=0;
    for(int i=1;i<=n;i++)
    {
        adj[i].clear();
        adjnew[i].clear();
        vis[i]=0;
    }
    for(int i=1;i<n;i++)
    {
        int u,v,w;
        u=readInt(1,n,' ');
        v=readInt(1,n,' ');
        w=readInt(0,1,'\n');
        adj[u].pb(mp(v,w));
        adj[v].pb(mp(u,w));
        assert(u!=v);
    }
    checktree(1);
    for(int i=1;i<=n;i++)
    {
        assert(vis[i]==1);
        vis[i]=0;
    }
    dfs(1);
    for(int i=1;i<=n;i++)
    {
        for(auto it:adj[i])
        {
            if(vis[it.first]==0 && vis[i]==0)
                adjnew[i].pb(it.first);
            else if(vis[it.first]==0)
                adjnew[1].pb(it.first);
        }
    }
    for(int i=1;i<=n;i++)
        vis[i]=0;
    subtreesz(1);
    vector <int> fun;
    for(auto it:adjnew[1])
        fun.pb(subtree[it]);
    sort(all(fun));
    int afford=0;
    if(alreadyaffected>k)
    {
        cout<<-1<<'\n';
        return;
    }
    for(auto it:fun)
    {
        if((alreadyaffected+it)<=k)
        {
            alreadyaffected+=it;
            afford++;
        }
        else
            break;
    }
    cout<<fun.size()-afford<<'\n';
}
int main()
{
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
    ios_base::sync_with_stdio(false);
    cin.tie(NULL),cout.tie(NULL);
    int T=readInt(1,1000,'\n');
    while(T--)
        solve();
    assert(getchar()==-1);
    cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC << "ms\n";
}