#10之后的都tle了

#include <iostream>
using namespace std;
int main() {
	int op;
	long long n,m,q,k,x,count=0,l[200001]={0},s[200001]={0};
	cin >> n >> m >> q >> k;
	for (long long a = 0; a < q; a++) {
		cin >> op >> x;
		if (op == 1){
			++l[x];
			if(l[x]==k)
			l[x]=0;}
		else
		{	++s[x];
		if(s[x]==k)
		s[x]=0;}
	}
	for (long long i = 1; i <= n; i++)
		for (long long j = 1; j <= m; j++)
            if(l[i]+s[j]&&l[i]+s[j]!=k)
                count++;
	cout << count;
	return 0;
}