#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <set>
#include <map>
#include <climits>
#include <queue>
#include <fstream>
#include <sstream>
#include <math.h>

using namespace std;

int main()
{
    int t;
    int n, m;
    vector<pair<int, int>> breaks;
    vector<pair<int, int>> friendBreaks;

    cin >> t;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        int first, second;
        cin >> first >> second;
        breaks.push_back(pair<int, int>(first, second));
    }
    cin >> m;
    for (int i = 0; i < m; i++)
    {
        int first, second;
        cin >> first >> second;
        friendBreaks.push_back(pair<int, int>(first, second));
    }

    int sum = 0;
    int breakIndex = 0;
    int friendBreakIndex = 0;
    while (breakIndex < breaks.size() && friendBreakIndex < friendBreaks.size())
    {
        pair<int, int> match = pair<int, int>(max(breaks[breakIndex].first, friendBreaks[friendBreakIndex].first), min(breaks[breakIndex].second, friendBreaks[friendBreakIndex].second));
        if (match.first > match.second)
        {
            if (breaks[breakIndex].first > friendBreaks[friendBreakIndex].second)
            {
                friendBreakIndex++;
                continue;
            }
            else
            {
                breakIndex++;
                continue;
            }
        }
        if (match.first > breaks[breakIndex].first + t)
        {
            breakIndex++;
            continue;
        }
        sum += match.second - match.first + 1;
        if (breaks[breakIndex].second < friendBreaks[friendBreakIndex].second)
        {
            breakIndex++;
        }
        else if (breaks[breakIndex].second > friendBreaks[friendBreakIndex].second)
        {
            breaks[breakIndex].first = friendBreaks[friendBreakIndex].second;
            friendBreakIndex++;
        }
        else
        {
            breakIndex++;
            friendBreakIndex++;
        }
    }

    cout << sum;
}