#include <bits/stdc++.h>

#define rint register int

#define int long long
#define endl '\n'

using namespace std;

const int N = 2e5 + 5;

int n, A, B;
int a[N], b[N], p[N];
int res;
bool in[N];

mt19937 rnd(time(0));
void solve() 
{
    int na = 0, nb = 0;
    
    for (rint i = 1; i <= n; i++)
    {
		if (!in[i]) na += a[i];
		else nb += b[i];
	}
    int now = na * nb;
    int times = 4e4 + 5;
	while (times--) 
	{
        int x = rand() % n + 1;
        if (!in[x]) 
		{
            if (now < ((na - a[x]) * (nb + b[x])))
            {
                in[x] ^= 1;
				na -= a[x]; 
				nb += b[x]; 
				now = na * nb;				
			}
        } 
		else 
		{
            if (now < (na + a[x]) * (nb - b[x]))
            {
                in[x] ^= 1;
				na += a[x]; 
				nb -= b[x];
				now = na * nb;				
			} 
        }
    }
    res = max(res, now);
}

void work() 
{
    for (rint i = 1; i <= n; i++)
    {
		cin >> a[i] >> b[i];
		p[i] = i;
	}
    res = 0;
    int times = 30;
    while (times--)
	{
        random_shuffle(p + 1, p + n + 1);
        for (rint i = 1; i <= n / 2; i++)
        {
			in[p[i]] = 1;
		}
		for (rint i = n / 2 + 1; i <= n; i++)
		{
			in[p[i]] = 0;
		}
        solve();
    }
    cout << res << endl;
}

signed main() 
{
    int T;
    cin >> T >> n >> A >> B;
    while (T--) work();
    return 0;
}