#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define pb push_back
#define fi first
#define se second
#define debug(x) cout << #x << " => " << x << "\n";
const long long mod = 1e9 + 7;
int n, m, p, q, ans;
int a[100005], b[100005], c[100005];
int x[100005], y[100005], z[100005];
vector <pair<int,pair<int,int>>> e[2];
int mst[2];
int optAns, tmpAns;
struct {
int par[100005], cost[100005];
int find(int u) {
if(par[u] == u) return u;
return par[u] = find(par[u]);
}
int join(int u, int v) {
u = find(u);
v = find(v);
if(u == v) return 0;
par[u] = v;
return 1;
}
int join(int u, int v, int EdgeWeight) {
u = find(u);
v = find(v);
if(u == v) return 0;
par[u] = v;
cost[v] = cost[v] + cost[u] + min(mst[0], EdgeWeight);
tmpAns += min(mst[0], EdgeWeight);
return 1;
}
} dsu[2];
void solve () {
cin >> n >> m >> p >> q;
// dalam negeri
for(int i = 1; i <= p; i++) {
cin >> a[i] >> b[i] >> c[i];
ans += n * c[i];
e[1].pb({c[i], {a[i], b[i]}});
}
// luar negeri
for(int i = 1; i <= q; i++) {
cin >> x[i] >> y[i] >> z[i];
ans += m * z[i];
e[0].pb({z[i], {x[i], y[i]}});
}
for(int i = 1; i <= n; i++) {
dsu[0].par[i] = i;
}
sort(e[0].begin(), e[0].end());
sort(e[1].begin(), e[1].end());
for(auto i : e[0]) {
int u = i.se.fi, v = i.se.se, w = i.fi;
if(dsu[0].join(u, v)) {
mst[0] += w;
}
}
for(int i = 1; i <= m; i++) {
dsu[1].par[i] = i;
}
for(auto i : e[1]) {
int u = i.se.fi, v = i.se.se, w = i.fi;
if(dsu[1].join(u, v)) {
mst[1] += w;
}
}
for(int i = 1; i <= m; i++) {
dsu[1].par[i] = i;
}
tmpAns = 0;
tmpAns += mst[1] + mst[0];
for(auto i : e[1]) {
int u = i.se.fi, v = i.se.se, w = i.fi * (n - 1);
dsu[1].join(u, v, w);
}
// debug(mst[0]);
// debug(mst[1]);
// debug(tmpAns);
// debug(ans);
ans = max(0ll, ans - tmpAns);
cout << ans << "\n";
}
signed main () {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
solve ();
}
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