#include<bits/stdc++.h>
#define int long long
using namespace std;
int f[50010][20];
int n;
int m,s,t;
struct Node{
	int x,y;
};
vector<Node> v[50010];
struct node{
	int now,k,ans;
	bool operator<(const node &m)const{
		return m.ans>m.ans;
	}
};
priority_queue<node> q;
int k1;
int minn=INT_MAX;
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	cin>>n>>m>>k1>>s>>t;
	for(int i=1;i<=m;i++){
		int x,y,z;
		cin>>x>>y>>z;
		v[x].push_back({y,z});
		v[y].push_back({x,z});
	}
	memset(f,127,sizeof(f));
	q.push({s,k1,0});
	f[s][k1]=0;
	while(!q.empty()){
		node k=q.top();
		q.pop();
		if(k.now==t){
			minn=min(minn,k.ans);
			continue;
		}
		for(int i=0;i<v[k.now].size();i++){
			if(f[v[k.now][i].x][k.k-1]>k.ans&&k.k>0){
				f[v[k.now][i].x][k.k-1]=k.ans;
				q.push({v[k.now][i].x,k.k-1,k.ans});
			}
			if(f[v[k.now][i].x][k.k]>k.ans+v[k.now][i].y){
				f[v[k.now][i].x][k.k]=k.ans+v[k.now][i].y;
				q.push({v[k.now][i].x,k.k,k.ans+v[k.now][i].y});
			}
		}
	}
	cout<<minn;
	return 0;
}