import java.util.*;
import java.io.*;

public class stacking {
	public static void main(String[] args) throws Exception {
		Scanner in = new Scanner(new File("stacking.in"));

		int StackCount = in.nextInt();
		int InstructionCount = in.nextInt();

		int[] stacks = new int[StackCount];
		for (int i = 0; i < InstructionCount; i ++) {   	// haybales count from 0
			int from = in.nextInt() - 1;		// -1 for array referencing
			int to = in.nextInt() - 1;			// -1 for array referencing
			//add 1 haybale from arrays 'from' to 'to'

			for (int j = from; j <= to; j ++) { //adding 1
				stacks[j] ++;
			}
		}

		int result = 0;

		/* for (int a = 0; a <stacks.length; a ++) { 	//checking if numbers are sorted correctly
			System.out.println(stacks[a]);
		}
		*/

		//sort the values in ascending order

		Arrays.sort(stacks);

		int index = StackCount/2;

		result = stacks[index];

		PrintWriter out = new PrintWriter(new File("stacking.out"));
		System.out.println(result);
		out.println(result);
		in.close();
		out.close();
	}

}