#include<bits/stdc++.h>
using std::cin;
using std::cout;
using std::endl;
using ll = long long;
using std::vector;
#define rep(i,j,k) for(int i=int(j); i<int(k); i++)
#define REP(i,j,k) for(int i=int(j); i<=int(k); i++)
const ll inf = (1ll<<60);

int main(){
    ll t; cin >> t;
    while(t--){
        ll N, M, K; cin >> N >> M >> K;
        vector<vector<ll>> data(N);
        rep(i,0,M){
            ll index, val; cin >> index >> val;
            data[index-1].push_back(val);
        }
        //(y-x)^2-(y-(x-1))^2 = 2x-2y-1
        vector<ll> sum(N);
        rep(i,0,N){
            for(auto p:data[i]){
                sum[i] += -p*2-1;
            }
        }
        ll left = -inf, right = inf;
        while(left+1 < right){
            ll mid = (left+right)/2;
            ll cnt = 0;
            rep(i,0,N){
                ll a = 2*data[i].size();
                //ax+sum[i] ≤ mid
                //ax ≤ mid-sum[i]
                //x ≤ (mid-sum[i])/a
                if(0 < a){
                    ll x = std::max(0ll, (mid-sum[i])/a);
                    cnt += x;
                }
                else if(0 <= mid) cnt += inf;
                if(K <= cnt) break;
            }
            if(K <= cnt) right = mid;
            else left = mid;
        }
        ll ans = 0, cnt = 0;
        bool flag = false;
        rep(i,0,N){
            if(data[i].empty()){
                flag = true;
                continue;
            }
            ll a = 2*data[i].size();
            ll x = std::max(0ll, (left-sum[i])/a);
            ans += x*(x+1)/2*a+sum[i]*x;
            cnt += x;
        }
        if(flag && 0<=right) cnt = K;
        ans += (K-cnt)*right;
        rep(i,0,N){
            for(auto p:data[i]) ans += p*p;
        }
        cout << ans << endl;
    }
}