CUBE-T181: Copying is not Permitted

#include <bits/stdc++.h>
using namespace std;

typedef long long lli;
typedef pair<int, int> pii;
typedef tuple<int, int, int> tiii;

const int N = 4e4;
const int P = 5e4;

vector<tiii> edges;
int ds[N + 1], sz[N + 1], nVertex, nCopy;
pii copying[P + 1];

int dsFind(int u){
    if(ds[u] == u){
        return u;
    }
    return ds[u] = dsFind(ds[u]);
}

bool isDisconnect(int upbWeight){
    for(int i = 1; i <= nVertex; ++i){
        ds[i] = i;
        sz[i] = 1;
    }
    for(tiii e : edges){
        int w = get<0>(e);
        int u = get<1>(e);
        int v = get<2>(e);
        if(w >= upbWeight){
            break;
        }
        u = dsFind(u);
        v = dsFind(v);
        if(u != v){
            if(sz[u] < sz[v]){
                swap(u, v);
            }
            ds[v] = u;
            sz[u] += sz[v];
        }
    }
    for(int i = 1; i <= nCopy; ++i){
        if(dsFind(copying[i].first) == dsFind(copying[i].second)){
            return false;
        }
    }
    return true;
}

int main(){

    int nEdge;
    scanf("%d%d%d", &nVertex, &nEdge, &nCopy);
    int mxFriendship = 1;
    for(int i = 1; i <= nEdge; ++i){
        int u, v, w;
        scanf("%d%d%d", &u, &v, &w);
        edges.emplace_back(w, u, v);
        mxFriendship = max(mxFriendship, w);
    }
    sort(edges.begin(), edges.end());

    for(int i = 1; i <= nCopy; ++i){
        int u, v;
        scanf("%d%d", &u, &v);
        copying[i] = pii(u, v);
    }

    int l = 1;
    int r = mxFriendship + 1;
    int ans = 1;
    while(l <= r){
        int m = ((lli)l + r) / 2;
        if(isDisconnect(m)){
            ans = max(ans, m);
            l = m + 1;
        } else {
            r = m - 1;
        }
    }
    if(ans == mxFriendship + 1){
        cout << "-1";
    } else {
        cout << ans;
    }

    return 0;
}