import java.util.Scanner;

public class olimpiada {
    public static void main(String[] args) {
        //input
        Scanner scanner = new Scanner(System.in);
        String[] temp = scanner.nextLine().split(" ");
        int n = Integer.parseInt(temp[0]);
        if(n < 1 || n > 100000) return;
        int k = Integer.parseInt(temp[1]);
        if(k < 1 || k > 20) return;
        int[][] timetable = new int[k][2];
        for(int i = 0; i < k; i++) {
            temp = scanner.nextLine().split(" ");
            timetable[i][0] = Integer.parseInt(temp[0]);
            timetable[i][1] = Integer.parseInt(temp[1]);
            if(timetable[i][1] > 2*n) return;
            if(timetable[i][0] < 0 || timetable[i][0] > timetable[i][1]) return;
        }


        //calculating
        int[][] timeGaps = new int[1][2];
        timeGaps[0][0] = 0;
        timeGaps[0][1] = 0;

        for(int i = 0; i < k; i++) {
            int amount = timetable[i][1] - timetable[i][0]+1;
            int[][] timeGapsTemp = new int[amount * timeGaps.length][2];
            int index = 0;
            for(int j = 0; j < timeGaps.length; j++) {
                for (int l = 0; l < amount; l++) {
                    timeGapsTemp[index][(i+1) % 2] = timeGaps[j][(i+1) % 2];
                    int tempTime = timetable[i][0] - timeGaps[j][0] - timeGaps[j][1] + l;
                    if (tempTime > n)
                        continue;
                    timeGapsTemp[index][i % 2] += tempTime;
                    int timeLeft = 2 * n - timeGapsTemp[index][0] - timeGapsTemp[index][1];
                    if(timeGapsTemp[index][i % 2] == n && timeGapsTemp[index][(i+1) % 2] + timeLeft == n) {
                        System.out.println("YES");
                        System.out.println(i+1);
                        return;
                    }
                    index++;
                }
            }
            timeGaps = timeGapsTemp;
        }
        System.out.println("NO");
    }
}