#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------

int T;
int N,M,K;
ll A[202020],B[202020],C[202020],X[202020];

ll hoge(ll v) {
	ll sum=0;
	int i;
	FOR(i,N) {
		X[i]=0;
		if(A[i]==0) {
			if(v>=0) X[i]=K;
		}
		else {
			ll t=v-A[i]-B[i]+1;
			if(t>=0) X[i]=(t+2*A[i]-1)/(2*A[i]);
		}
		sum+=X[i];
	}
	return sum;
}


void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>T;
	while(T--) {
		cin>>N>>M>>K;
		FOR(i,N) A[i]=B[i]=C[i]=0;
		FOR(i,M) {
			cin>>x>>y;
			x--;
			A[x]++;
			B[x]-=2*y;
			C[x]+=1LL*y*y;
		}
		
		ll ret=-1LL<<30;
		for(i=30;i>=0;i--) {
			if(hoge(ret+(1LL<<i))<=K) ret+=(1LL<<i);
		}
		hoge(ret);
		ll sumY=0;
		ll sumX=0;
		FOR(i,N) {
			sumX+=X[i];
			sumY+=A[i]*X[i]*X[i]+B[i]*X[i]+C[i];
		}
		sumY+=(ret+1)*(K-sumX);
		
		
		
		cout<<sumY<<endl;
	}
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}