#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<ll,int>
const int N = 3e6+10;
const ll inf = 1e17;

ll read(){
    ll x = 0,f = 1;char c = getchar();
    for(;c < '0' || c > '9';c = getchar())if(c == '-')f = -1;
    for(;c >= '0' && c <= '9';c = getchar())x = (x<<1) + (x<<3) + c-'0';
    return x * f;
}


int n,m,k,s,t;
struct made{
    int ver,nx;ll ed;
}e[N<<1];
int hd[N],tot;
void add(int x,int y,ll z){e[++tot] = {y,hd[x],z},hd[x] = tot;}


ll d[N];
bool v[N];
void dij(int u){
    memset(v,0,sizeof v);
    for(int i = 1;i <= n * (k+1);i++)d[i] = inf;
    priority_queue<pii,vector<pii>,greater<pii> >q;
    q.push(make_pair(0,u)),d[u] = 0;
    while(!q.empty()){
        int x = q.top().second;q.pop();
        if(v[x])continue;
        v[x] = 1;
        for(int i = hd[x];i;i = e[i].nx){
            int y = e[i].ver;ll z = e[i].ed;
            if(d[y] > d[x] + z){
                d[y] = d[x] + z;
                q.push(make_pair(d[y],y));
            }
        }
    }
}
int main(){
    freopen("move.in","r",stdin);
    freopen("move.out","w",stdout);
    //编号0~n-1
    n = read(),m = read(),k = read(),s = read() + 1,t = read() + 1;
    for(int i = 1;i <= m;i++){
        int x = read() + 1,y = read() + 1;ll z = read();
        add(x,y,z),add(y,x,z);
        for(int j = 1;j <= k;j++){
            add(x + n * (j-1),y + n * j,0);
            add(x + n * j,y + n * j,z);
            add(y + n * j,x + n * j,z);
        }
    }
    dij(s);
    ll ans = inf;
    for(int i = 0;i <= k;i++)ans = min(ans,d[t + n * i]);
    printf("%lld\n",ans);
    
    return 0;
    
}