#include <bits/stdc++.h>
#define rep(i,n) for(int i=0; i<(int)(n); i++)

using namespace std;
using LL = long long;

class UnionFind {
public:
    vector <LL> par;
    vector <LL> siz;

    UnionFind(LL sz_): par(sz_), siz(sz_, 1LL) {
        for (LL i = 0; i < sz_; ++i) par[i] = i;
    }
    void init(LL sz_) {
        par.resize(sz_);
        siz.assign(sz_, 1LL);
        for (LL i = 0; i < sz_; ++i) par[i] = i;
    }

    LL root(LL x) {
        while (par[x] != x) {
            x = par[x] = par[par[x]];
        }
        return x;
    }

    bool unite(LL x, LL y) {
        x = root(x);
        y = root(y);
        if (x == y) return false;
        if (siz[x] < siz[y]) swap(x, y);
        siz[x] += siz[y];
        par[y] = x;
        return true;
    }

    bool same(LL x, LL y) {
        return root(x) == root(y);
    }

    LL size(LL x) {
        return siz[root(x)];
    }
};

struct edge{
    int from, to;
    LL cost;
    edge(int from, int to, LL cost): from(from), to(to), cost(cost) {}

    bool operator<(const edge &e) const{
        return cost < e.cost;
    }
};
vector<edge> es;
LL kruskal(int siz){
    sort(es.begin(),es.end());
    UnionFind uf(siz);
    LL res=0;
    rep(i,es.size()){
        edge e=es[i];
        if(!uf.same(e.from, e.to)){
            uf.unite(e.from, e.to);
            res+=e.cost;
        }
    }
    return res;
}

int main(){
	int L, R;
	cin >> L >> R;
	for(int i=L; i<R; i++){
		for(int j=2; i*j<=R; j++){
			es.emplace_back(i,i*j,0);
		}
		es.emplace_back(i,i+1,1);
	}
	LL ans=kruskal(R+1);
	cout << ans << endl;

	return 0;
}