#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
#include <deque>
#include <tuple>

using namespace std;
signed  main()
{
    cin.tie(nullptr);
    cout.tie(nullptr);
    ios_base::sync_with_stdio(false);
    int t, n;
    cin >> t >> n;
    vector<pair<int, int>> me;
    vector<pair<int, int>> huno;
    for (int i = 0; i < n; i++)
    {
        int x, y;
        cin >> x >> y;
        me.push_back(make_pair(x, y));
    }
    int m;
    cin >> m;
    for (int i = 0; i < m; i++)
    {
        int x, y;
        cin >> x >> y;
        huno.push_back(make_pair(x, y));
    }
    int ans = 0;
    int lgame = me[0].first-1;
    int mei = 0;
    int hui = 0;
    while (true)
    {
        if (me[mei].first <= huno[hui].first && me[mei].second >= huno[hui].first)
        {
            if (lgame + t+1 >= huno[hui].first && lgame != me[mei].second)
            {
                ans += min(me[mei].second, huno[hui].second) - huno[hui].first + 1;
            }
        }
        if (me[mei].first >= huno[hui].first && me[mei].first <= huno[hui].second)
        {
            ans += min(me[mei].second, huno[hui].second) - me[mei].first + 1;
        }
        if (me[mei].second >= huno[hui].second)
        {
            if (lgame < huno[hui].second)
            {
                lgame = huno[hui].second;
                hui++;
            }
            if (hui == m)
            {
                cout << ans;
                return 0;
            }
        }
        else {
            mei++;
            if (mei == n)
            {
                cout << ans;
                return 0;
            }
            lgame = me[mei].first - 1;
        }
    }
}
/*
25 7
1 8 3 15 4 20 16
*/