#include <iostream>
using namespace std;
 
int main () 
{
	int x, n;
	cin >> x >> n;
	int N[n][4];
	for (int i = 0; i < n; i++)
		for (int j = 0; j < 4; j++)
			cin >> N[i][j];
	for (int i = 0; i < n; i++) 
		for (int j = 0; j < n; j++) 
			for (int q = 0; q < 4; q++)
				if ((N[i][1] > N[j][1] || N[i][3] > N[j][3]) || ( (N[i][1] == N[j][1] || N[i][3] == N[j][3] ) && (N[i][0] > N[j][0] || N[i][2] > N[j][2]) ) )
					swap(N[i][q], N[j][q]);
	for (int i = 0; i < n; i++) {
		if (x >= N[i][0] && x <= N[i][2]) 
			N[i][1] < N[i][3] ? x = N[i][0] : x = N[i][2];
		for (int j = 0; j < 4; j++)
			N[i][j] = 0;
	}
	cout << x;
 
	return 0;
}

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MzAgNAoyNSAzNSA0MCAzMAoxIDMyIDIwIDMwCjMzIDIyIDUwIDI5CjE4IDEwIDMzIDE5

30 4
25 35 40 30
1 32 20 30
33 22 50 29
18 10 33 19