#include <bits/stdc++.h>
#define fin cin
#define fout cout

#define maxn 10003
using namespace std;
struct Edge {
	int v, w, next;
}edge[200003];
struct Data {
	int dis, pos;
	bool operator < (const Data &x) const {
		return x.dis < dis;
	}
};
int n, m, k, s, t;
int cnt, head[maxn], dis[maxn], vis[maxn];
priority_queue<Data> q;
void add(int u, int v, int w) {
	cnt++;
	edge[cnt].v = v;
	edge[cnt].w = w;
	edge[cnt].next = head[u];
	head[u] = cnt;
}
void dijkstra(int start) {
	// init
	fill(dis + 1, dis + n + 1, INT_MAX);
	dis[start] = 0;
	
	q.push((Data){dis[start], start});
	while (q.size()) {
		Data f = q.top(); q.pop();
		int pos = f.pos;
		
		if (vis[pos]) {
			continue;
		}
		vis[pos] = 1;
		
		for (int i = head[pos]; i; i = edge[i].next) {
			int v = edge[i].v, w = edge[i].w;
			if (dis[v] > dis[pos] + w) {
				dis[v] = dis[pos] + w;
				if (vis[v] == 0) {
					q.push((Data){dis[v], v});
				}
			}
		}
	}
}
int main() {
	ifstream fin("light.in");
	//ofstream fout("light.out");
	ios::sync_with_stdio(0); fin.tie(0); fout.tie(0);

	fin >> n >> m >> k;
	fin >> s >> t;
	for (int i = 1; i <= m; i++) {
		int u, v, w;
		fin >> u >> v >> w;
		add(u, v, w);
		add(v, u, w);
		for (int j = 1; j <= k; j++) {
			add(u + j * n, v + j * n, w);
			add(v + j * n, u + j * n, w);
			add(u + j * n - n, v + j * n, 0);
			add(v + j * n - n, u + j * n, 0);
		}
	}
	
	dijkstra(s);
	
	int ans = INT_MAX;
	for (int i = 0; i <= k; i++) {
		if (dis[t + i * n] < ans)
		ans = dis[t + i * n];
	}
	fout << ans;
	return 0;
}