/* Murad Eynizade */

#include <bits/stdc++.h>
#define int long long
#define FAST_READ ios_base::sync_with_stdio(0);cin.tie(0);
#define F first
#define S second

using namespace std;

const int sz = 1001;

int n , m , x , y , w , s , t , used[sz][3] , d[sz][3];

vector< pair<int,int> >v[sz][3];

bool f = false;

priority_queue< pair<int,int> >pq;

void dijkstra(int s,int di) {
    for (int i = 1;i<=n;i++)d[i][di] = 1000000000000000LL;
    d[s][di] = 0;
    pq.push({0 , s});
    while (!pq.empty()) {
        int u = pq.top().S;
        pq.pop();
        for (auto to : v[u][di]) {
            if (d[to.F][di] > d[u][di] + to.S) {
                d[to.F][di] = d[u][di] + to.S;
                pq.push({-d[to.F][di] , to.F});
            }
        }
    }
}

void dfs(int s,int di) {
    if (f)return;
    if (s == t)return;
    used[s][di] = 1;
    for (auto to : v[s][di]) {
        if (f)return;
        if (d[to.F][di] < d[s][di]) {
            assert(s != t);
            if (used[to.F][3 - di] == 1 && to.F != t) {
                f = true;
                return;
            }
            if (used[to.F][3 - di] == 0)dfs(to.F , 3 - di);
        }
    }
    used[s][di] = 2;
}

int ans[sz][3];

int solve(int s,int di) {
    if (ans[s][di] != -1)return ans[s][di];
    int mx = -1000000000000000LL;
    for (auto to : v[s][di]) {
        if (d[to.F][di] < d[s][di]) mx = max(mx , to.S + solve(to.F , 3 - di));
    }
    ans[s][di] = mx;
    return mx;
}

main()
{
    FAST_READ;
    cin>>n>>s>>t;
    cin>>m;
    while (m--) {
        cin>>x>>y>>w;
        if (x == y)continue;
        v[x][1].push_back({y,w});
        v[y][1].push_back({x,w});
    }
    cin>>m;
    while (m--) {
        cin>>x>>y>>w;
        if (x == y)continue;
        v[x][2].push_back({y,w});
        v[y][2].push_back({x,w});
    }
    dijkstra(t , 1);
    dijkstra(t , 2);
    dfs(s , 1);
    if (f) {
        cout<<-1<<endl;
        exit(0);
    }
    memset(ans , -1 , sizeof(ans));
    ans[t][1] = ans[t][2] = 0;
    cout<<solve(s , 1)<<endl;
}