#include <stdio.h>

 #include <string.h>

 #include <queue>

 using namespace std;

 const int maxn=;

 const int maxm=maxn*maxn;

 const long long INF=1LL<<;

 int vis[maxn],head[maxn];

 int n,m,cnt = ;

 struct node

 {

     int u,v;

     long long w;

     int next;

 } edge[maxm];

 inline void add(int u,int v,long long w)

 {

     edge[cnt].u = u;

     edge[cnt].v = v;

     edge[cnt].w = w;

     edge[cnt].next = head[u];

     head[u] = cnt++;

 }

 void spfa(int s, long long dis[])

 {

     queue<int>q;

     q.push(s);

     vis[s] = ;

     dis[s] = ;

     while(!q.empty())

     {

         int u = q.front();

         q.pop();

         vis[u] = ;

         for (int j = head[u]; j!=-; j= edge[j].next)

         {

             int v = edge[j].v;

             long long w = edge[j].w;

             if (dis[u]+w < dis[v])

             {

                 dis[v] = dis[u]+w;

                 q.push(v);

                 vis[v] = ;

             }

         }

     }

 }

 void init()

 {

 }

 int main()

 {

     int u,v;

     long long w;

     long long dis1[maxn],dis2[maxn];

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

     {

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

         {

             vis[i] = ;

             dis1[i] = INF;

             dis2[i] = INF;

             head[i] = -;

         }

         cnt = ;

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

         {

             scanf("%d %d %lld",&u,&v,&w);

             add(u,v,w);

             add(v,u,w);

         }

         int s,e;

         long long min=INF;

         scanf("%d %d",&s,&e);

         spfa(s,dis1);//求出起点到所有点的最短路径

         spfa(e,dis2);//求出终点到所有点的最短路径

         for (int i = ; i < cnt; i++)//遍历所有的边

         {

             u = edge[i].u;

             v = edge[i].v;

             w = edge[i].w;

             if (dis1[u]+dis2[v]+w/ < min)//S->u+e->v+w/2即为改变后的权值，找出最小的

                 min = dis1[u]+dis2[v]+w/;

         }

         if(min==INF)

         {

             puts("No solution");

             continue;

         }

         printf("%lld\n",min);

     }

     return ;

 }