//
// Created by hanyu on 2019/7/14.
//
#include<iostream>
#include<algorithm>
#include<queue>
#include<map>
#include<cstring>
#include<cstdio>
using namespace std;
typedef long long ll;
#define MAX 0x3f3f3f3f
int T,n;
const int maxn=1005;
bool book[maxn];
int lu[maxn][maxn];
int d[maxn];

void spfa(int a)
{
    int now;
    memset(book,false,sizeof(book));
    memset(d,MAX,sizeof(d));
    queue<int>qu;
    d[a]=0;
    book[a]=true;
    qu.push(a);
    while(!qu.empty())
    {
        now= qu.front();
        qu.pop();
        book[now]=false;
        for(int i=1;i<=n;i++)
        {
            if(d[i]>d[now]+lu[now][i])
            {
                d[i]=d[now]+lu[now][i];
                if(!book[i])
                {
                    qu.push(i);
                    book[i]=true;
                }
            }
        }
    }
}

int main()
{
    while(~scanf("%d%d",&T,&n)) {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= i; j++) {
                if (i == j)
                    lu[i][j] = 0;
                else
                    lu[i][j] = lu[j][i] = MAX;
            }
        }
        int x, y, z;
        for (int i = 1; i <= T; i++) {
            scanf("%d%d%d", &x, &y, &z);
            if(z<lu[x][y])
                 lu[x][y] = lu[y][x] = z;
        }
        spfa(1);
        printf("%d\n", d[n]);
    }
    return 0;
}