#include<bits/stdc++.h>
#include<unordered_set>
#include<unordered_map>
using namespace std;
#define int long long
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define all(a) a.begin(),a.end()
#define rall(c) (c).rbegin(),(c).rend()
#define mp make_pair
#define endl '\n'
typedef long long ll;
typedef pair<ll,ll> pll;
typedef long double ld;
const ll inf=1e9+7;
const ll mod=1e9+7;
//高速化Union-Find木


int siz[200010];
int par[200010];
int depth[200010];
void init(int n){
  for(int i=0;i<=n;i++){
      par[i]=i;
      depth[i]=0;
  }
  rep(i,n+1){
      siz[i]=1;
  }
}
int root(int x){
  return par[x]==x?x:par[x]=root(par[x]);
}
bool same(int x,int y){
  return root(x)==root(y);
}
void unite(int x,int y){
  x=root(x);
  y=root(y);
  ll sx=siz[x];
  ll sy=siz[y];
  if(x==y)return;
  if(depth[x]<depth[y]){
      par[x]=y;
  }else{
      par[y]=x;
      if(depth[x]==depth[y])depth[x]++;
  }
  siz[root(x)]=sx+sy;
}
signed main(){
    ll l,r;cin>>l>>r;
    ll ans=0;
    init(r);
    REP(i,l,r+1){
        ll d=2;
        while(d*i<=r){
            unite(i,d*i);
            d++;
        }
    }
    vector<ll>used(r+1);
    REP(i,l,r+1){
        if(used[root(i)])continue;
        ans++;
        used[root(i)]=1;
    }
    ans--;
    cout<<ans<<endl;
}