/* ***********************************************

 Author        :Sun Yuefeng

 Created Time  :2016/10/22 14:18:06

 File Name     :A.cpp

 ************************************************ */

 #include<cstdio>

 #include<iostream>

 #include<algorithm>

 #include<cmath>

 #include<cstring>

 #include<string>

 #include<bitset>

 #include<map>

 #include<set>

 #include<stack>

 #include<vector>

 #include<queue>

 #include<list>

 #define M(a,b) memset(a,b,sizeof(a))

 using namespace std;

 typedef long long ll;

 const int inf=0x3f3f3f3f;

 const int maxn=1e3+;

 const int mod=1e7+;

 int dx[]= {,,,-,,-,,-};

 int dy[]= {,-,,,-,,,-};

 int n,m;

 int way[maxn][maxn];

 int dis[maxn];

 bool vis[maxn];

 void dijkstra(int x){

     for(int i=;i<=m;i++){

         dis[i]=inf;

         vis[i]=false;

     }

     dis[x]=;

     for(int i=;i<=m;i++){

         int k=-;

         int min=inf;

         for(int j=;j<=m;j++){

             if(!vis[j]&&dis[j]<min){

                 min=dis[j];

                 k=j;

             }

         }

         if(k==-) break;

         vis[k]=true;

         for(int j=;j<=m;j++){

             if(!vis[j]&&dis[j]>dis[k]+way[j][k]){

                 dis[j]=dis[k]+way[j][k];

             }

         }

     }

 }

 int main()

 {

     //freopen("in.txt","r",stdin);

     //freopen("out.txt","w",stdout);

     while(~scanf("%d%d",&n,&m)){

         int a,b,v;

         M(way,inf);

         for(int i=;i<n;i++){

             scanf("%d%d%d",&a,&b,&v);

             if(way[a][b]>v){

                 way[a][b]=v;

                 way[b][a]=v;

             }

         }

         dijkstra();

         int min=inf;

         printf("%d\n",dis[m]);

     }

     return ;

 }