//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <unordered_map>
#include <climits>
#include <set>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <chrono>
#include <complex>
#include <regex>
#include <locale>
#include <random>
#include <cassert>
#include <type_traits>

using namespace std;

// typedef
//------------------------------------------
typedef long long LL;
typedef vector<int> VI;
typedef vector<bool> VB;
typedef vector<char> VC;
typedef vector<double> VD;
typedef vector<string> VS;
typedef vector<LL> VLL;
typedef vector<VI> VVI;
typedef vector<VB> VVB;
typedef vector<VS> VVS;
typedef vector<VLL> VVLL;
typedef vector<VVI> VVVI;
typedef vector<VVLL> VVVLL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef pair<int, string> PIS;
typedef pair<string, int> PSI;
typedef pair<string, string> PSS;
typedef vector<PII> VPII;
typedef vector<PLL> VPLL;
typedef vector<VPII> VVPII;
typedef vector<VPLL> VVPLL;
typedef vector<VS> VVS;
typedef map<int, int> MII;
typedef map<LL, LL> MLL;
typedef map<string, int> MSI;
typedef map<int, string> MIS;

// container util
//------------------------------------------

#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define EACH(i, arr) for(typeof((arr).begin()) i=(arr).begin(); i!=(arr).end(); ++i)
#define EXIST(str, e) ((str).find(e)!=(str).end())
#define COUNT(arr, v) count((arr).begin(), (arr).end(), v)
#define SEARCH(v, w) search((v).begin(), (v).end(), (w).begin(), (w).end())
#define SORT(c) sort((c).begin(),(c).end())
#define RSORT(c) sort((c).rbegin(),(c).rend())
#define REVERSE(c) reverse((c).begin(), (c).end())
#define ROTATE_LEFT(arr, c) rotate((arr).begin(), (arr).begin()+(c), (arr).end())
#define ROTATE_RIGHT(arr, c) rotate((arr).rbegin(), (arr).rbegin() + (c), (arr).rend())
#define SUMI(arr) accumulate((arr).begin(), (arr).end(), 0)
#define SUMD(arr) accumulate((arr).begin(), (arr).end(), 0.)
#define SUMLL(arr) accumulate((arr).begin(), (arr).end(), 0LL)
#define MULD(arr) accumulate((arr).begin(), (arr).end(), 1., multiplies<double>())
#define UB(arr, n) upper_bound((arr).begin(), (arr).end(), n)
#define LB(arr, n) lower_bound((arr).begin(), (arr).end(), n)
#define PB push_back
#define MP make_pair
#define ft first
#define sd second


// input output
//------------------------------------------
#define GL(s) getline(cin, (s))
#define INIT() std::ios::sync_with_stdio(false);std::cin.tie(0)
#define OUT(d) std::cout<<(d)
#define OUT_L(d) std::cout<<(d)<<endl
#define FOUT(n, data) std::cout<<std::fixed<<std::setprecision(n)<<(data)
#define FOUT_L(n, data) std::cout<<std::fixed<<std::setprecision(n)<<(data)<<"\n"
#define EL() printf("\n")
#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v) {std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}
#define Yes() printf("Yes\n")
#define No() printf("No\n")
#define YES() printf("YES\n")
#define NO() printf("NO\n")
#define Yay() printf("Yay!\n")
#define Nnn() printf(":(\n")
#define CE(x, y) ((x + y - 1) / (y))


template<typename T1, typename T2>
istream &operator>>(istream &in, pair<T1, T2> &p) {
    in >> p.first >> p.second;
    return in;
}

template<typename T>
istream &operator>>(istream &in, vector<T> &v) {
    for (auto &x: v)
        in >> x;
    return in;
}


template<typename T1, typename T2>
ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) {
    out << "[" << p.first << ", " << p.second << "]" << "\n";
    return out;
}

template<class T1, class T2>
inline bool chmin(T1 &a, T2 b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template<class T1, class T2>
inline bool chmax(T1 &a, T2 b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}


//repetition
//------------------------------------------
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define RFOR(i, a, b) for(int i=(b)-1;i>=(a);--i)
#define REP(i, n)  FOR(i,0,n)
#define RREP(i, n) for(int i = n-1;i >= 0;i--)
#define FORLL(i, a, b) for(LL i=LL(a);i<LL(b);++i)
#define RFORLL(i, a, b) for(LL i=LL(b)-1;i>=LL(a);--i)
#define REPLL(i, n) for(LL i=0;i<LL(n);++i)
#define RREPLL(i, n) for(LL i=LL(n)-1;i>=0;--i)
#define FOREACH(x, arr) for(auto &(x) : (arr))

// Option + Control + K  Terminal
// Command + Control + K    Run
// Command + b   EOF



//------------------------------------------
//------------------------------------------

template<class T>
inline bool ISPRIME(const T x) {
    if (x <= 1)return false;
    for (T i = 2; i * i <= x; i++)if (x % i == 0)return false;
    return true;
}

template<typename T>
vector<T> DIVISOR(T n) {
    vector<T> v;
    for (T i = 1; i * i <= n; ++i) {
        if (n % i == 0) {
            v.push_back(i);
            if (i != n / i) {
                v.push_back(n / i);
            }
        }
    }
    sort(v.begin(), v.end());
    return v;
}

template<typename T>
vector<vector<T>> DIVISOR_ALL(T n) {
    vector<vector<T>> res(n + 1);
    for (T i = 1; i <= n; i++) {
        for (T j = i; j <= n; j += i) {
            res[j].push_back(i);
        }
    }
    return res;
}

template<class T>
vector<bool> ERATOSTHENES(const T n) {
    vector<bool> arr(n + 1, true);
    arr[0] = arr[1] = false;
    for (T i = 2; i * i <= n; i++) {
        if (arr[i]) {
            for (T j = i * 2LL; j <= n; j += i) {
                arr[j] = false;
            }
        }
    }
    return arr;
}

template<class T>
vector<T> ERATOSTHENES_VALUE(const T n) {
    vector<bool> primes = ERATOSTHENES(n);
    vector<T> results;
    for (int i = 0; i <= n; i++) if (primes[i]) results.emplace_back(i);
    return results;
}

// a <= x < b
template<typename T>
vector<bool> ERATOSTHENES(const T a, const T b) {
    vector<bool> small = ERATOSTHENES(b);
    vector<bool> prime(b - a, true);

    for (T i = 2; i * i <= b; i++) {
        if (small[i]) {
            for (T j = max(2LL, (a + i - 1) / i) * i; j < b; j += i) {
                prime[j - a] = false;
            }
        }
    }

    return prime;
}

// O(n (logn)^2)
template<typename T>
vector<T> SMALLEST_PRIME_FACTORS(T n) {
    vector<T> spf(n + 1);
    for (T i = 0; i <= n; i++) spf[i] = i;
    for (T i = 2; i * i <= n; i++) {
        if (spf[i] == i) {
            for (T j = i * i; j <= n; j += i) {
                spf[j] = i;
            }
        }
    }
    return spf;
}


template<typename T>
vector<pair<T, T>> FACTORIZATION(T x) {
    vector<pair<T, LL>> ans;
    for (T i = 2; i * i <= x; i++) {
        if (x % i == 0) {
            T count = 0;
            while (x % i == 0) {
                count++;
                x /= i;
            }
            ans.push_back(make_pair(i, count));
        }
    }
    if (x != 1) ans.push_back(make_pair(x, 1));
    return ans;
}

// O(logn)
template<typename T>
vector<T> FACTORIZATION(T x, vector<T> &spf) {
    vector<T> ret;
    while (x != 1) {
        ret.push_back(spf[x]);
        x /= spf[x];
    }
    sort(ret.begin(), ret.end());
    return ret;
}

constexpr int MAX = 200020;

struct UnionFind {

    vector<int> par;
    vector<int> sizes;

    UnionFind(int n)
            : par(n), sizes(n, 1) {
        for (int i = 0; i < n; i++) {
            par[i] = i;
        }
    }

    int find(int x) {
        return x == par[x] ? x : par[x] = find(par[x]);
    }

    bool unite(int x, int y) {
        x = find(x);
        y = find(y);
        if (x == y) return false;
        if (sizes[x] < sizes[y]) swap(x, y);
        par[y] = x;
        sizes[x] += sizes[y];
        return true;
    }

    bool same(int x, int y) {
        return find(x) == find(y);
    }

    int get_size(int x) {
        return sizes[find(x)];
    }

    bool all_same() {
        bool good = true;
        for (int i = 0, n = par.size(); i < n; i++) if (find(0) != find(i)) good = false;
        return good;
    }

    int get_connectivity() {
        set<int> s;
        for (int i = 0, n = par.size(); i < n; i++) s.insert(find(i));
        return s.size();
    }

};

int main() {

    int L, R;
    cin >> L >> R;

    UnionFind UF(R + 1);

    for (int i = L; i <= R; i++) {
        int x = i;
        while (x + i <= R) {
            x += i;
            UF.unite(i, x);
        }
    }

    int ans = UF.get_connectivity();
    cout << ans - L - 1<< endl;
}