#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[9]={0,1,-1,0,1,1,-1,-1,0};
const ll dx[9]={1,0,0,-1,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
int main(){
    vector<ll> dp(1e7,1);
    vector<ll> prime;
    for(int i=2;i<1e7;i++){
        if(!dp[i])continue;
        prime.push_back(i);
        for(int j=i*2;j<1e7;j+=i)dp[j]=0;
    }
    ll l,r;cin >> l >> r;
    vector<ll> dp2(r-l+1);
    for(ll i=0;i<r-l+1;i++)dp2[i]=l+i;
    vector<ll> sq(r-l+1);
    for(auto p:prime){
        ll idx=l/p*p;if(idx<l)idx+=p;
        for(;idx<=r;idx+=p){
            ll cnt=0;
            while(dp2[idx-l]%p==0){
                dp2[idx-l]/=p;cnt++;
            }
            if(cnt>1)sq[idx-l]=1;
        }
    }
    ll p=max(sqrt(l)-1,2.0);
    for(;p*p<=r;p++){
        if(l<=p*p)sq[p*p-l]++;
    }
    ll ans=0;
    for(auto p:sq)if(p)ans++;
    cout << r-l+1-ans << endl;

}