#include <iostream>
#include <vector>
#include <queue>

template <class T>
using MaxHeap = std::priority_queue<T>;

using namespace std;
using lint = long long;

void solve() {
    int n, m, k;
    cin >> n >> m >> k;

    vector<lint> cnt(n, 0), first(n, 0);
    lint ans = 0;

    while (m--) {
        int x;
        lint y;
        cin >> x >> y;
        --x;

        ++cnt[x];
        first[x] += y * 2 - 1;
        ans += y * y;
    }

    MaxHeap<pair<lint, int>> heap;
    for (int i = 0; i < n; ++i) {
        heap.emplace(first[i], i);
    }

    while (k--) {
        auto [d, i] = heap.top();
        heap.pop();

        ans -= d;
        heap.emplace(d - cnt[i] * 2, i);
    }

    cout << ans << "\n";
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int q;
    cin >> q;
    while (q--) solve();

    return 0;
}