#include<bits/stdc++.h> 
#define ll long long 
#define LL __int128_t 
#define PB push_back
#define Pair pair<int, int>
#define MK make_pair
#define fi first
#define se second
#define FOR(i, x, y) for (decay<decltype(y)>::type i = (x), _##i = (y); i <= _##i; ++i)
#define FORD(i, x, y) for (decay<decltype(x)>::type i = (x), _##i = (y); i >= _##i; --i)
#define debug(x) cout<< "\033 -> "<<#x<<": "<<x<<endl
using namespace std;
const int N(200005);
#define X first
#define W second
#define Pair pair<int, int>
vector<Pair> e[N];
int f[N], ans2;
void dfs(int x, int fa)
{
	int lk1 = 0, lk2 = 0;
	for(auto &to : e[x]) if(to.X != fa)
	{
		dfs(to.X, x);
		if(f[to.X]+to.W > lk1)
		{
			lk2 = lk1;
			lk1 = f[to.X]+to.W;
		}
		else if(f[to.X]+to.W > lk2) lk2 = f[to.X]+to.W;
	}
	f[x] = lk1;
	ans2 = max(ans2, lk1 + lk2);
}
int main() 
{ 
	//freopen("1.in","r",stdin); 
	ios::sync_with_stdio(false); 
	cin.tie(NULL);
	int n, k; cin >> n >> k;
	ll ans = 0;
	FOR(i, 1, n-1)
	{
		int x, y, w; cin >> x >> y >> w;
		ans += w;
		e[x].PB(MK(y, w));
		e[y].PB(MK(x, w));
	}
	if(k >= 2)
	{
		cout<<ans<<endl;
		return 0;
	}
	dfs(1, 0);
	cout<<ans2<<endl;
	return 0; 
}