#include<bits/stdc++.h>
using namespace std;
int n,m,k,s,t; 
int head[5000005],dis[5000005],vis[5000005],num_edge;
struct node
{
	int to,w,next;	
}edge[5000005];
void add_edge(int from, int to, int w)
{
	edge[++num_edge].next=head[from];
	edge[num_edge].to=to;
	edge[num_edge].w=w;
	head[from]=num_edge;
} 
priority_queue<pair<int,int>,vector<pair<int,int> >,greater<pair<int,int> > > Q;
void dijkstra(int s)
{
    memset(dis,0x3f,sizeof(dis));
    dis[s]=0;
    Q.push(make_pair(0,s));
    while(!Q.empty())
    {
        int u=Q.top().second;
        Q.pop();
        if(!vis[u])
        {
            vis[u]=1;
            for(int i=head[u];i;i=edge[i].next)
            {
                int to=edge[i].to;
                if(dis[to]>dis[u]+edge[i].w) 
                {
                    dis[to]=dis[u]+edge[i].w;
                    Q.push(make_pair(dis[to],to));
                }
            }
        }
    }
}
int main ()
{
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	cin>>n>>m>>k>>s>>t;
	for (int i=1;i<=m;i++)
	{
		int u,v,w;
		cin>>u>>v>>w;
		add_edge(u,v,w);
		add_edge(v,u,w);
		for (int j=1;j<=k;j++)
		{
			add_edge(u+(j-1)*n,v+j*n,0);
			add_edge(u+j*n,v+j*n,w);
			add_edge(v+j*n,u+j*n,w);
		}
	}
	for(int i=1;i<=k;i++)
	{
		add_edge(t+(i-1)*n,t+i*n,0);
	}
	dijkstra(s);
	cout<<dis[t+k*n];
	return 0;
}