#include <cstdio>
#include <iostream>
#include <vector>
#include <set>
using namespace std;

#define ll long long
#define mp make_pair
#define pb push_back

const int LEN = 100009;
const ll INF = 200000000000000000;

int n, m;
int s, t;
int A, B;

vector <pair<int, ll> > g[LEN];
ll d[LEN][2];

int main() {
    scanf("%d%d%d%d", &n, &m, &s, &t);
    s--;
    t--;

    int a, b, c;
    for (int i = 0; i < m; i++) {
        scanf("%d%d%d", &a, &b, &c);

        g[a - 1].pb(mp(b - 1, c));
        g[b - 1].pb(mp(a - 1, c));
    }

    scanf("%d%d", &A, &B);

    for (int i = 0; i < n; i++) {
        d[i][0] = INF;
        d[i][1] = INF;
    }

    d[s][0] = 0;
    d[s][1] = 0;

    set <pair<ll, int> > heap;
    for (int i = 0; i < n; i++) {
        heap.insert(mp(d[i][0], i));
    }
    for (int q = 0; q < n; q++) {
        int v = (*(heap.begin())).second;
        heap.erase(heap.begin());

        for (int i = 0; i < g[v].size(); i++) {
            if (g[v][i].second > A)
                continue;

            if (d[g[v][i].first][0] > d[v][0] + g[v][i].second) {
                heap.erase(mp(d[g[v][i].first][0], g[v][i].first));
                d[g[v][i].first][0] = min(d[g[v][i].first][0], d[v][0] + g[v][i].second);
                heap.insert(mp(d[g[v][i].first][0], g[v][i].first));
            }
        }
    }

    heap.clear();

    for (int i = 0; i < n; i++)
        heap.insert(mp(d[i][1], i));
    for (int q = 0; q < n; q++) {
        int v = (*(heap.begin())).second;
        heap.erase(heap.begin());

        for (int i = 0; i < g[v].size(); i++) {
            if (g[v][i].second < B)
                continue;

            if (d[g[v][i].first][1] > min(d[v][0] + g[v][i].second, d[v][1] + g[v][i].second)) {
                heap.erase(mp(d[g[v][i].first][1], g[v][i].first));
                d[g[v][i].first][1] = min(d[g[v][i].first][1], min(d[v][0] + g[v][i].second, d[v][1] + g[v][i].second));
                heap.insert(mp(d[g[v][i].first][1], g[v][i].first));
            }
        }
    }

    if (d[t][0] == INF && d[t][1] == INF)
        printf("-1");
    else
        printf("%lld", min(d[t][0], d[t][1]));
}