#include<bits/stdc++.h>
#define INF 0x3f3f3f3f
using namespace std;
inline int read(){
    int x=0,f=1;
    char ch=getchar();
    while(ch<'0'||ch>'9')
    {
        if(ch=='-')
            f=-1;
        ch=getchar();
    }
    while(ch>='0' && ch<='9')
        x=x*10+ch-'0',ch=getchar();
    return x*f;
}
inline void write(int x)
{
    if(x<0)
        putchar('-'),x=-x;
    if(x>9)
        write(x/10);
    putchar(x%10+'0');
    return;
}
int n,m,s,k,e;
priority_queue<pair<int,int>,vector<pair<int,int> >,greater<pair<int,int> > > q;
struct Node {
    int v,w;
    Node(int _v,int _w){
        v=_v;  w=_w;
    }
};
vector<Node> g[100005];
bool vis[100005];
int d[100005];
int ans=INF;
void dij(){
	for(int i=1;i<=n*k;i++) d[i]=INF;
	memset(vis,false,sizeof(vis));
	int u;
	d[s]=0;
	q.push(make_pair(0,s));
	while(!q.empty()){
		int u=q.top().second; q.pop();
		if(vis[u]) continue;
		vis[u]=true;
		for(int i=0;i<g[u].size();i++){
			int v=g[u][i].v;int w=g[u][i].w;
			if(d[v]>d[u]+w&&!vis[v]) {
				d[v]=d[u]+w;
				q.push(make_pair(d[v],v));
			}
		}
	}
}
signed main()
{
// 	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	n=read(),m=read(),k=read();
	s=read(),e=read();
	for(int i=1;i<=m;i++){
		int u=read(),v=read(),w=read();
		for(int j=0;j<=k;j++){
			g[v+j*n].push_back(Node(u+j*n,w));
			g[u+j*n].push_back(Node(v+j*n,w));
			if(j!=k) {
				g[v+j*n].push_back(Node(u+(j+1)*n,0));
				g[u+j*n].push_back(Node(v+(j+1)*n,0));
			}
		}
	}
	dij();
	for(int i=0;i<=k;i++) ans=min(ans,d[e+n*i]);
	cout<<ans;
    return 0;
}