#include <bits/stdc++.h>

#define int long long
#define For(i, l, r) for(int i = l; i <= r; i ++)

using namespace std;

const int N = 10110;

void in(int &x) {scanf("%lld", &x);}

int n, m, T, A, B;
int a[N], b[N];

signed main()
{
	in(T); in(n); in(A); in(B);
	while(T --)
	{
		For(i, 1, n) in(a[i]), in(b[i]);
		int ans = 0, U = (1 << n) - 1;
		For(s, 1, U)
		{
			int sa = 0, sb = 0;
			For(i, 1, n) if(s >> (i - 1) & 1) sa += a[i]; else sb += b[i];
			ans = max(ans, sa * sb);
		}
		printf("%lld\n", ans);
	}
}