source_code: import java.util.Scanner;
  
  /**
   * @author Son-Huy TRAN
   * 
   */
  public class P15A_CottageVillage {
  
  	/**
  	 * @param args
  	 */
  	public static void main(String[] args) {
  		Scanner scanner = new Scanner(System.in);
  
  		int n = scanner.nextInt();
  		int t = scanner.nextInt();
  		scanner.nextLine();
  
  		int[] x = new int[n];
  		int[] a = new int[n];
  
  		for (int i = 0; i < n; i++) {
  			x[i] = scanner.nextInt();
  			a[i] = scanner.nextInt();
  			scanner.nextLine();
  		}
  
  		scanner.close();
  
  		for (int i = 0; i < n - 1; i++) {
  			for (int j = i + 1; j < n; j++) {
  				if (x[i] > x[j]) {
  					swap(x, i, j);
  					swap(a, i, j);
  				}
  			}
  		}
  
  		int countPositions = 2;
  
  		for (int i = 1; i < n; i++) {
  			double left = x[i - 1] + a[i - 1] * 1.0 / 2;
  			double right = x[i] - a[i] * 1.0 / 2;
  			double length = right - left;
  
  			if (length == (double) t) {
  				countPositions++;
  			} else if (length > t) {
  				countPositions += 2;
  			}
  		}
  
  		System.out.println(countPositions);
  	}
  
  	private static void swap(int[] numbers, int i, int j) {
  		int temp = numbers[i];
  		numbers[i] = numbers[j];
  		numbers[j] = temp;
  	}
  }
  