#include<iostream>
#include<cmath>
#include<cstring>
#include<queue>

using namespace std;
int Read(){
    int x = 0; char c = getchar();
    while(c<'0'||c>'9') {
        c = getchar();
    }
    while(c>='0'&&c<='9'){
        x = x*10 + c -'0';
        c = getchar();
    }
    return x;
}
int ans[2000005];
int head[2000005];
int cnt = 0;
struct EDGE{
    int Next;
    int To;
    int Weight;
}edge[2000005];
void addedge(int x, int v, int w){
    cnt++;
    edge[cnt].Next = head[x];
    edge[cnt].To = v;
    edge[cnt].Weight = w;
    head[x] = cnt;
}
struct Priority{
    int ans;
    int id;
    bool operator<(const Priority&A)const{
        return ans > A.ans;
    }
};
bool vis[2000005];
void dijkstra(int n, int m, int k, int s, int t){
    priority_queue<Priority>q;
    q.push({0,s});
    while(!q.empty()){
        Priority temp = q.top();
        q.pop();
        if(vis[temp.id]==1) continue;
            vis[temp.id] = 1;
        for(int i = head[temp.id]; i!=0; i = edge[i].Next){
            int v = edge[i].To;
            if(ans[v] > ans[temp.id] + edge[i].Weight){
                ans[v] = ans[temp.id] + edge[i].Weight;
                    q.push({ans[v],v});
            }
        }
    }
    return ;
}
int main(){
    int n, m, k;
    n =Read();m = Read(); k = Read();
    int s, t;
    s =Read(); t = Read();
    for(int i = 1; i<=m; i++){
        int a, b, c;
        a = Read(); b = Read(); c = Read();
        addedge(a,b,c);
        addedge(b,a,c);
        for(int j = 1; j<=k; j++){
            addedge(a + (j-1)*n, b + j*n, 0);
            addedge(b + (j-1)*n, a + j*n, 0);
            addedge(a + j*n, b + j*n, c);
            addedge(b + j*n, a + j*n, c);
        }
      }
    memset(ans,0x3f,sizeof(ans));
    ans[s] = 0;
    for(int i = 1; i<=k; i++){
        addedge(t+(i-1)*n, t+i*n, 0);
    }


    dijkstra(n, m, k, s, t);
    int minn = 0x3f3f3f3f;
    for(int i = 0; i<=k; i++){
        minn = min(minn, ans[t+i*n]);
    }
    cout<<minn;
    return 0;

}