#include<bits/stdc++.h>
#define MAXN 200005
#define LL long long
using namespace std;

bool OPT;
bool vis[MAXN];
LL n,m,u,v,w,pos,ans;
LL head[MAXN];

struct Edge
{
	LL u,v,w,nxt;
}e[2*MAXN];

void addEdge(LL u,LL v,LL w)
{
	e[++pos]={u,v,w,head[u]};
	head[u]=pos;
}

LL DFS(LL st)
{
	if(head[st]==0) return 0;
	LL res=0;
	for(LL i=head[st];i;i=e[i].nxt)
		if(!vis[e[i].v]) vis[e[i].v]=true,res=max(res,(DFS(e[i].v)+e[i].w));
	return res;
}

void solve1()
{
	vis[1]=true;
	printf("%lld",m-DFS(1));
}

LL DP(LL st)
{
	if(head[st]==0) return 0;
	LL max1=0,max2=0;
	for(LL i=head[st];i;i=e[i].nxt){
		LL v=e[i].v,w=e[i].w;
		if(!vis[v]){
			vis[v]=true;
			LL res=DP(v);
			if(res+w>=max1) max2=max1,max1=res+w;
			else if(res+w>=max2) max2=res+w;
		}
	}
	ans=max(ans,max1+max2);
	return max1;
}

void solve2()
{
	vis[1]=true;
	DP(1);
	printf("%lld",m-ans);
}

int main()
{
	scanf("%d",&OPT);
	scanf("%lld",&n);
	for(int i=1;i<n;i++){
		scanf("%lld%lld%lld",&u,&v,&w);
		addEdge(u,v,w);
		addEdge(v,u,w);
		m+=2*w;
	}
	if(OPT==0) solve1();
	else solve2();
}