rt

#include <bits/stdc++.h>
using namespace std;

bool bm[5010], gm[5010];//打扫过的行、列

int main(){
    int n, m, b, g;
    cin >> n >> m >> b >> g;
    for (int i = 1; i <= b; i++){
        int l, r;
        cin >> l >> r;
        for (int j = l; j <= r; i++){
            bm[j] = 1;
        }
    }
    for (int i = 1; i <= g; i++){
        int l, r;
        cin >> l >> r;
        for (int j = l; j <= r; i++){
            gm[j] = 1;
        }
    }
    int s1 = 0, s2 = 0;//计数器
    for (int i = 1; i <= n; i++){
        if (bm[i] == 1){
            s1++;
        }
    }
    for (int i = 1; i <= m; i++){
        if (gm[i] == 1){
            s2++;
        }
    }
    cout << s1*s2;
    return 0;
}