#include <iostream>
#include <vector>

using namespace std;

class int2
{
	public:
	int x;
	int y;
};

int main()
{
	int h, a, e;
	cin >> h;

	vector<bool> adamcont;
	vector<bool> evacont;
	for (int i = 0; i < h; i++)
	{
		adamcont.push_back(false);
		evacont.push_back(false);
	}

	vector<int2> Adam;
	
	cin >> a;
	for (int i = 0; i < a; i++)
	{
		int2 in;
		cin >> in.x >> in.y;
		in.x--;
		in.y--;
		Adam.push_back(in);
	}

	for (int i = 0; i < a; i++)
	{
		adamcont[Adam[i].x] = true;
		adamcont[Adam[i].y] = true;
	}

	vector<int2> Eva;

	cin >> e;
	for (int i = 0; i < e; i++)
	{
		int2 in;
		cin >> in.x >> in.y;
		in.x--;
		in.y--;
		Eva.push_back(in);
	}

	for (int i = 0; i < e; i++)
	{
		evacont[Eva[i].x] = true;
		evacont[Eva[i].y] = true;
	}

	int c = 0;
	vector<int2> ans;

	bool ad = false;
	bool ev = false;


	for (int i = 0; i < h; i++)
	{
		if (adamcont[i])
		{
			ad = !ad;
		}
		if (evacont[i])
		{
			ev = !ev;
		}
		if (i == h - 1)
		{
			break;
		}
		if (ad && ev)
		{
			int k = i + 1;
			while (!adamcont[k] && !evacont[k] && k < h - 1)
			{
				k++;
			}

			if (k == h - 1)
			{
				break;
			}
			int2 a;
			a.x = i + 1;
			a.y = k + 1;
			if (a.x != a.y)
			{
				c++;
				ans.push_back(a);
			}
			if (adamcont[k])
			{
				ad = false;
			}
			else
			{
				ev = false;
			}
			i = k;
		}
	}

	cout << c << endl;
	for (int2 a : ans)
	{
		cout << a.x << " " << a.y << endl;
	}
	cout << endl;
}