#include <vector>
#include <math.h>
#include <iostream>
#include <algorithm>
using namespace std;

#define FOR(i, N) for(int i=0; i<(N); i++)
#define REP(i, N) for(int i=1; i<=(N); i++)

typedef pair<int, int> Edge;

struct Union_Find {
    vector<int> parent, rank;
    Union_Find(int n){
        parent.resize(n, 0);
        rank.resize(n, 0);
        for (int i=0; i<n; i++){
            parent[i] = i;
            rank[i] = 0;
        }
    }
    
    int get_parent(int x){
        if (x != parent[x]){
            parent[x] = get_parent(parent[x]);
        }
        return parent[x];
    }

    void unite(int x, int y){
        x = get_parent(x);
        y = get_parent(y);
        
        if (rank[x] > rank[y]){
            parent[y] = x;
        }else{
            parent[x] = y;
            if (rank[x] == rank[y]){
                rank[y]++;
            }
        }
        return;
    }
};



int main() {
    int L, R;
    vector<pair<int, Edge>> edges;
    
    cin >> L >> R;
    for(int i=L; i<=R; i++){
        if (i < R)
            edges.push_back({1, {i, i+1}});
        
        for(int j=1; j<=sqrt(i); j++){
            
            if (i % j == 0){
                if (L <= j && j < i){
                    edges.push_back({0, {i, j}});
                }
                if (L <= (i/j) && (i/j) < i && j != (i/j)){
                    edges.push_back({0, {i, i/j}});
                }
            }
        }
    }
    
    sort(edges.begin(), edges.end());

    int V = R - L + 1;
    int v_cnt = 0;
    int answer = 0;
    
    Union_Find uf(V);
    
    for (auto e : edges){
        int cost = e.first;
        int e1 = e.second.first - L;
        int e2 = e.second.second - L;
        
        if (uf.get_parent(e1) != uf.get_parent(e2)){
            uf.unite(e1, e2);
            answer += cost;
            v_cnt++;
        }
        
        if (v_cnt == V-1){
            break;
        }
    }
    
    cout << answer << endl;;
    
	return 0;
}