#include <bits/stdc++.h>
using namespace std;
#define rep(i, n)  for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define pb emplace_back
#define lb(v,k) (lower_bound(all(v),(k))-v.begin())
#define ub(v,k) (upper_bound(all(v),(k))-v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define dame(a) {out(a);return 0;}
#define decimal cout<<fixed<<setprecision(15);
#define all(a) a.begin(),a.end()
#define rsort(a) {sort(all(a));reverse(all(a));}
#define dupli(a) {sort(all(a));a.erase(unique(all(a)),a.end());}
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
typedef tuple<ll,ll,ll,ll> PPP;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vvvvi=vector<vvvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vb=vector<bool>;
using vvb=vector<vb>;
const ll inf=1001001001001001001;
const ll INF=1001001001;
const ll mod=1000000007;
const double eps=1e-10;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
template<class T> bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void outset(T s){auto itr=s.begin();while(itr!=s.end()){if(itr!=s.begin())cout<<' ';cout<<*itr;itr++;}cout<<'\n';}
void outs(ll a,ll b){if(a>=inf-100)out(b);else out(a);}
ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);}
ll modpow(ll a,ll b){ll res=1;a%=mod;while(b){if(b&1)res=res*a%mod;a=a*a%mod;b>>=1;}return res;}

int main(){
    ll tt;cin>>tt;
    rep(ttt,tt){
        ll n,m,k;cin>>n>>m>>k;
        ll mx=sqrt(1000000000000000000/m)+2;
        ll mx2=10000000000000;
        vvi g(n);
        rep(i,m){
            ll a,b;cin>>a>>b;g[a-1].pb(b);
        }
        auto cost=[&](ll i,ll u){
            ll res=0;
            for(ll x:g[i])res+=(x-u)*(x-u);
            return res;
        };
        vi best(n);
        rep(i,n){
            ll l=0,r=mx;
            while(r-l>3){
                ll nl=(l*2+r)/3,nr=(l+r*2)/3;
                if(cost(i,nl)<cost(i,nr))r=nr;
                else l=nl;
            }
            ll mi=inf;
            REP(j,l,r+1)if(chmin(mi,cost(i,j)))best[i]=j;
        }
        // outv(best);
        ll cur=0;
        rep(i,n)cur+=best[i];
        cur-=k;
        if(cur>0){
            ll ok=mx2,ng=-1;
            while(ok-ng>1){
                ll md=(ok+ng)/2;
                ll sum=0;
                rep(i,n){
                    ll OK=best[i],NG=-1;
                    while(OK-NG>1){
                        ll MD=(OK+NG)/2;
                        if(cost(i,MD)-cost(i,MD+1)>md)NG=MD;
                        else OK=MD;
                    }
                    sum+=best[i]-OK;
                }
                if(sum>=cur)ok=md;
                else ng=md;
            }
            {
                rep(i,n){
                    ll OK=best[i],NG=-1;
                    while(OK-NG>1){
                        ll MD=(OK+NG)/2;
                        if(cost(i,MD)-cost(i,MD+1)>ok)NG=MD;
                        else OK=MD;
                    }
                    best[i]=OK;
                }
            }
            ll a=0,b=0;
            rep(i,n){
                a+=cost(i,best[i]);b+=best[i];
            }
            a-=(k-b)*ok;
            out(a);
        }
        else{
            ll ok=mx2,ng=-1;
            while(ok-ng>1){
                ll md=(ok+ng)/2;
                ll sum=0;
                rep(i,n){
                    ll OK=best[i],NG=mx+1;
                    while(NG-OK>1){
                        ll MD=(OK+NG)/2;
                        if(cost(i,MD)-cost(i,MD-1)>md)NG=MD;
                        else OK=MD;
                    }
                    sum+=OK-best[i];
                }
                if(sum>=-cur)ok=md;
                else ng=md;
            }
            // out(ok);
            {
                rep(i,n){
                    ll OK=best[i],NG=mx+1;
                    while(NG-OK>1){
                        ll MD=(OK+NG)/2;
                        if(cost(i,MD)-cost(i,MD-1)>ok)NG=MD;
                        else OK=MD;
                    }
                    best[i]=OK;
                }
            }
            ll a=0,b=0;
            rep(i,n){
                a+=cost(i,best[i]);b+=best[i];
            }
            a-=(b-k)*ok;
            out(a);
        }
    }
}