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();
        UnionFindTree uft = new UnionFindTree(right + 1);
        for (int i = left; i <= right; i++) {
            for  (int j = 2; j * i <= right; j++) {
                uft.unite(i, i * j);
            }
        }
        HashSet<Integer> set = new HashSet<>();
        for (int i = left; i <= right; i++) {
            set.add(uft.find(i));
        }
       System.out.println(set.size() - 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 (x == parents[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(y)] = find(x);
            }
        }
    }
}