#include<bits/stdc++.h>
using namespace std;
struct edge
{
    int to,dis,next;
};
edge e[2000010*2];
int head[2600],dis[2600],cnt;
bool vis[2600];
int n,m;
void add_edge(int u,int v,int w)
{
    ++cnt;
    e[cnt].dis=w;
    e[cnt].to=v;
    e[cnt].next=head[u];
    head[u]=cnt;
}
struct node
{
    int dis;
    int pos;
    bool operator <(const node &x)const
    {
       x.dis<dis; 
    }
};
priority_queue<node>q;
void dij()
{
    dis[1]=0;
    q.push((node){0,1});
    while(!q.empty())
    {
        node tmp=q.top();
        q.pop();
        int x=tmp.pos;
        if(vis[x]) continue;
        vis[x]=1;
        for(int i=head[x];i;i=e[i].next)
        {
            int y=e[i].to;
            if(dis[y]>dis[x]+e[i].dis)
            {
                dis[y]=dis[x]+e[i].dis;
                if(!vis[y])
                {
                    q.push((node){dis[y],y});
                }
            }
        }
    }
}
int main()
{
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++) dis[i]=1e9;
    for(int i=1;i<=m;i++)
    {
        int u,v,w;
        scanf("%d%d%d",&u,&v,&w);
        add_edge(u,v,w);
        add_edge(v,u,w);
    }
    dij();
    printf("%d",dis[n]);
    return 0;
}