// Videogame.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <vector>
using namespace std;
#define int long long
int T;
int lastPlayedGlobal;
struct interval {
    int beginning;
    int end;
};
char intersectionType(interval Me, interval Hano) {
    if (Me.beginning <= Hano.beginning && Me.end >= Hano.beginning) return 'M'; //Intersection when I start playing first
    if (Me.beginning >= Hano.beginning && Hano.end >= Me.beginning) return 'H'; //Intersection when Hano starts playing first
    return 'N'; //No intersection
}
int calcPlayTime(interval Me, interval Hano) {
    char iType = intersectionType(Me, Hano);
    if (iType == 'N') return 0;
    if (iType == 'H') return min(Hano.end, Me.end) - Me.beginning + 1;
    if (iType == 'M') {
        if (lastPlayedGlobal + T >= Hano.beginning) {
            return min(Hano.end, Me.end) - Hano.beginning + 1;
        }
        else return 0;
    }
}
signed main()
{
    cin >> T;
    int meIntervalCount, hanoIntervalCount;
    cin >> meIntervalCount;
    vector<interval> meIntervals;
    vector<interval> hanoIntervals;
    for (size_t i = 0; i < meIntervalCount; i++)
    {
        int a, b;
        cin >> a >> b;
        meIntervals.push_back({ a,b });
    }
    cin >> hanoIntervalCount;
    for (size_t i = 0; i < hanoIntervalCount; i++)
    {
        int a, b;
        cin >> a >> b;
        hanoIntervals.push_back({ a,b });
    }
    int hanoIntervalIndex = 0;
    int meIntervalIndex = 0;
    lastPlayedGlobal = meIntervals[0].beginning;
    int MaxPlayTime = 0;
    while (true) {
        MaxPlayTime+=calcPlayTime(meIntervals[meIntervalIndex], hanoIntervals[hanoIntervalIndex]);
        if (meIntervals[meIntervalIndex].end >= hanoIntervals[hanoIntervalIndex].end) {
            lastPlayedGlobal = hanoIntervals[hanoIntervalIndex].end;
            hanoIntervalIndex++;
            if (hanoIntervalIndex == hanoIntervalCount) {
                cout << MaxPlayTime << "\n";
                return 0;
            }
        }
        else {
            meIntervalIndex++;
            if (meIntervalIndex == meIntervalCount) {
                cout << MaxPlayTime << "\n";
                return 0;
            }
            else lastPlayedGlobal = meIntervals[meIntervalIndex].beginning;
        }
    }
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file