A

//Dijkstra
#include <iostream>
#include <algorithm>
#define Faster ios_base::sync_with_stdio(false),cin.tie(0)
#define Read freopen("in.txt","r",stdin),freopen("out.txt","w",stdout)
#define Close fclose(stdin),fclose(stdout)
const int maxn = 1000+5;
const int INF = 0xfffffff;
using namespace std;

int g[maxn][maxn];
bool v[maxn];
int dis[maxn];

int t, n;

//x 为起点
void dij(int x){
    for(int i = 0;i <= n;i++){
        dis[i] = g[x][i];
        v[i] = true;
    }
    v[x] = false;

    int Min, p;
    for(int i = 1;i <= n;i++){
        Min = INF;
        for(int j = 1;j <= n;j++){
            if(v[j] && dis[j] < Min){
                Min = dis[j];
                p = j;
            }
        }
        if(Min == INF)
            break;
        v[p] = false;
        for(int j = 1;j <= n;j++){
            if(v[j] && dis[p] + g[p][j] < dis[j]){
                dis[j] = dis[p] + g[p][j];
            }
        }
    }
}

int main(){
    Faster;
    cin >> t >> n;
    for(int i = 0;i <= n;i++){
        for(int j = 0;j <= n;j++)
            g[i][j] = INF;
    }
    for(int i = 0;i < t;i++){
        int x, y, z;
        cin >> x >> y >> z;
        if(g[x][y] > z)
            g[x][y] = g[y][x] = z;
    }
    dij(1);
    cout << dis[n] << endl;
    return 0;
}