#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <ctime>
#include <cassert>
#include <complex>
#include <string>
#include <cstring>
#include <chrono>
#include <random>
#include <bitset>
#include <fstream>
using namespace std;
#define int long long
#define ii pair <int, int>
#define app push_back
#define all(a) a.begin(), a.end()
#define bp __builtin_popcountll
#define ll long long
#define mp make_pair
#define x first
#define y second
#define Time (double)clock()/CLOCKS_PER_SEC
#define debug(x) std::cerr << #x << ": " << x << '\n';
#define FOR(i, n) for (int i = 0; i < n; ++i)
#define FORN(i, n) for (int i = 1; i <= n; ++i)
#define pb push_back
#define trav(a, x) for (auto& a : x)
using vi = vector<int>;
template <typename T>
std::istream& operator >>(std::istream& input, std::vector<T>& data)
{
    for (T& x : data)
        input >> x;
    return input;
}
template <typename T>
std::ostream& operator <<(std::ostream& output, const pair <T, T> & data)
{
    output << "(" << data.x << "," << data.y << ")";
    return output;
}
template <typename T>
std::ostream& operator <<(std::ostream& output, const std::vector<T>& data)
{
    for (const T& x : data)
        output << x << " ";
    return output;
}
ll div_up(ll a, ll b) { return a/b+((a^b)>0&&a%b); } // divide a by b rounded up
ll div_down(ll a, ll b) { return a/b-((a^b)<0&&a%b); } // divide a by b rounded down 
ll math_mod(ll a, ll b) { return a - b * div_down(a, b); }
#define tcT template<class T
#define tcTU tcT, class U
tcT> using V = vector<T>; 
tcT> void re(V<T>& x) { 
    trav(a, x)
        cin >> a;
}
tcT> bool ckmin(T& a, const T& b) {
    return b < a ? a = b, 1 : 0; 
} // set a = min(a,b)
tcT> bool ckmax(T& a, const T& b) {
    return a < b ? a = b, 1 : 0; 
}
ll gcd(ll a, ll b) {
    while (b) {
        tie(a, b) = mp(b, a % b);
    }
    return a;
}
signed main() {
    #ifdef LOCAL
    #else
    #define endl '\n'
    ios_base::sync_with_stdio(0); cin.tie(0);
    #endif
    int t;
    cin >> t;
    while (t--) {
        const int INF = 2e9+2007;
        int n, m, k;
        cin >> n >> m >> k;
        V <vi> a(n + 1);
        FOR (i, m) {
            int x, y;
            cin >> x >> y;
            a[x].app(y);
        }

        auto Cost = [&] (int c, int x) {
            int ans = 0;
            trav (e, a[c]) {
                ans += (e - x) * (e - x);
            }
            return ans;
        };  

        auto Get = [&] (int der) {
            int ans = 0;
            FORN (c, n) {
                int l = 0, r = INF;
                while (l < r - 1) {
                    int m = (l + r) / 2;
                    if (Cost(c, m) - Cost(c, m - 1) <= der) {
                        l = m;
                    }
                    else {
                        r = m;
                    }
                }
                ans += l;
            }
            return ans;
        };  

        int der = -INF;
        for (int bit = 40; bit >= 0; --bit) {
            int nu = der + (1ll << bit);
            if (nu < INF && Get(nu) <= k) {
                der = nu;
            }
        }
        auto Get_Cost = [&] (int der) {
            int ans = 0;
            FORN (c, n) {
                int l = 0, r = INF;
                while (l < r - 1) {
                    int m = (l + r) / 2;
                    if (Cost(c, m) - Cost(c, m - 1) <= der) {
                        l = m;
                    }
                    else {
                        r = m;
                    }
                }
                ans += Cost(c, l);
            }
            return ans;
        };

        /*
        debug(der);
        debug(Get(der));
        debug(Get_Cost(der));
        */
        
        cout << Get_Cost(der) + (k - Get(der)) * (der + 1) << endl;
    }
}