#include<bits/stdc++.h>
using namespace std;
#define pb(x) push_back(x)
#define ll long long
#define mk(x, y) make_pair(x, y)
#define lson l, m, rt<<1
#define mem(a) memset(a, 0, sizeof(a))
#define rson m+1, r, rt<<1|1
#define mem1(a) memset(a, -1, sizeof(a))
#define mem2(a) memset(a, 0x3f, sizeof(a))
#define rep(i, a, n) for(int i = a; i<n; i++)
#define ull unsigned long long
typedef pair<int, int> pll;
const double PI = acos(-1.0);
const double eps = 1e-8;
const int mod = 1e9+7;
const int inf = 1061109567;
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
const int maxn = 5e4+5;
int dis[12][60005], in[12][60005], num, head[maxn*2];
int n, m, k, s, t;
struct edge
{int to, nextt, w;
}e[maxn*2];
struct node
{int u, x;node(){}node(int u, int x):u(u),x(x){}
};
void init() {mem1(head);num = 0;
}
void add(int u, int v, int w) {e[num].to = v;e[num].nextt = head[u];e[num].w = w;head[u] = num++;
}
queue <node> q;
int dij() {mem2(dis);q.push(node(s, 0));dis[0][s] = 0;in[0][s] = 1;while(!q.empty()) {node tmp = q.front(); q.pop();int u = tmp.u, x = tmp.x;in[x][u] = 0;for(int i = head[u]; ~i; i = e[i].nextt) {int v = e[i].to;if(dis[x][v]>dis[x][u]+e[i].w) {dis[x][v] = dis[x][u]+e[i].w;if(!in[x][v]) {in[x][v] = 1;q.push(node(v, x));}}}if(x<k) {x++;for(int i = head[u]; ~i; i = e[i].nextt) {int v = e[i].to;if(dis[x][v]>dis[x-1][u]) {dis[x][v] = dis[x-1][u];if(!in[x][v]) {in[x][v] = 1;q.push(node(v, x));}}}}}int ans = inf;for(int i = 0; i<=k; i++)ans = min(ans, dis[i][t]);return ans;
}
int main()
{int x, y, z;cin>>n>>m>>k>>s>>t;init();while(m--) {scanf("%d%d%d", &x, &y, &z);add(x, y, z);add(y, x, z);}int ans = dij();cout<<ans<<endl;return 0;
}