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

int N,M,L,K,P;
vector<int> p[100005];
int rez = 0;
int dp[10005];

void flame_on(int K,int L)
{
    memset(dp,0,sizeof(dp));
    for (int i = 1 ; i <= K; i ++){
        for (int j = 0; j < p[i].size(); j ++){
            dp[p[i][j]]++;
        }
    }
    for (int i = K; i <= N; i ++){
        if ( i != K){
            for (int j = 0; j < p[i].size(); j++)
                dp[p[i][j]]++;
            for (int j = 0; j < p[i-K].size(); j ++)
                dp[p[i-K][j]]--;

        }
        int cnt = 0;
        for (int j = 1; j <= L; j ++){
            if (dp[j]>0)
                cnt++;
        }
        if (cnt == 0)
            rez++;
        for (int j = L+1; j <= M; j++){
            if ( dp[j-L] > 0)
                cnt--;
            if (dp[j] > 0)
                cnt++;
            if (cnt == 0){
                rez++;
            }
        }
    }
}
int main()
{
    //ifstream cin("44.txt");
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    cin >> N >> M >> K >> L >> P;
    for (int i = 0; i < P; i ++){
        int x,y; cin >> x >> y;
        p[x].push_back(y);
    }
    flame_on(K,L);
    if (K != L){
        //cout << "IN" << endl;
        flame_on(L,K);
    }
    cout << rez << '\n';
}