import java.util.*;

public class Main {
 	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int left = sc.nextInt();
		int right = sc.nextInt();
		if (left == 1) {
		    System.out.println(0);
		    return;
		}
		UnionFindTree uft = new UnionFindTree(right - left + 1);
		for (int i = left; i <= right / 2; i++) {
		    for (int j = 2; j * i <= right; j++) {
		        uft.unite(i - left, i * j - left);
		    }
		}
		System.out.println(uft.getCount() - 1);
	}
	static class UnionFindTree {
	    int[] parents;
	    
	    public UnionFindTree(int size) {
	        parents = new int[size];
	        for (int i = 0; i < size; i++) {
	            parents[i] = i;
	        }
	    }
	    
	    public int find(int x) {
	        if (parents[x] == x) {
	            return x;
	        } else {
	            return parents[x] = find(parents[x]);
	        }
	    }
	    
	    public boolean same(int x, int y) {
	        return find(x) == find(y);
	    }
	    public void unite(int x, int y) {
	        if (!same(x, y)) {
	            parents[find(x)] = find(y);
	        }
	    }
	    
	    public int getCount() {
	        HashSet<Integer> set = new HashSet<>();
	        for (int i = 0; i < parents.length; i++) {
	            set.add(find(i));
	        }
	        return set.size();
	    }
	}
}