#include <bits/stdc++.h>
using namespace std;
struct node
{
    int id, dis, cnt;
    bool operator<(const node &x) const
    {
        return dis > x.dis;
    }
};
struct edge
{
    int to, w;
};
const int LEN = 1e4 + 5;
int dist[LEN][11], n, m, k, s, t, ans = INT_MAX;
bool vis[LEN][11];
vector<edge> G[LEN];
priority_queue<node> q;
void dij(int s)
{
    // for (int i = 1; i <= n; i++) <----------- !!!!
    for (int i = 0; i < n; i++)
        for (int j = 0; j <= k; j++)
            dist[i][j] = INT_MAX;
    dist[s][0] = 0;
    q.push({s, 0, 0});
    while (!q.empty())
    {
        node u = q.top();
        q.pop();
        // printf("q.pop:    u.id = %d, u.dis = %d,u.cnt = %d\n", u.id, u.dis, u.cnt);
        if (vis[u.id][u.cnt])
        {
            // printf("continue: u.id = %d, u.cnt = %d\n", u.id, u.cnt);
            continue;
        }
        vis[u.id][u.cnt] = 1;
        for (int i = 0; i < G[u.id].size(); i++)
        {
            edge e = G[u.id][i];
            if (dist[u.id][u.cnt] + e.w < dist[e.to][u.cnt])
            {
                dist[e.to][u.cnt] = dist[u.id][u.cnt] + e.w;
                q.push({e.to, dist[e.to][u.cnt], u.cnt});
                // printf("q.push:   e.to = %d, dist[e.to][u.cnt] = %d, u.cnt = %d\n", e.to, dist[e.to][u.cnt], u.cnt);
            }
            if (u.cnt < k && dist[u.id][u.cnt] < dist[e.to][u.cnt + 1])
            {
                dist[e.to][u.cnt + 1] = dist[u.id][u.cnt];
                q.push({e.to, dist[e.to][u.cnt + 1], u.cnt + 1});
                // printf("q.push:   e.to = %d, dist[e.to][u.cnt + 1] = %d, u.cnt + 1 = %d\n", e.to, dist[e.to][u.cnt + 1], u.cnt + 1);
            }
        }
    }
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m >> k >> s >> t;
    for (int i = 1; i <= m; i++)
    {
        int a, b, c;
        cin >> a >> b >> c;
        G[a].push_back({b, c});
        G[b].push_back({a, c});
    }
    dij(s);
    for (int i = 0; i <= k; i++)
        ans = min(ans, dist[t][i]);
    cout << ans;
    // for (int i = 0; i <= k; i++)
    // {
    //     for (int j = 0; j < n; j++)
    //         cout << dist[j][i] << " ";
    //     cout << "\n";
    // }
    return 0;
}