#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES

#include <bits/stdc++.h>
using namespace std;
using i8  = int8_t;  using u8  = uint8_t;
using i16 = int16_t; using u16 = uint16_t;
using i32 = int32_t; using u32 = uint32_t;
using i64 = int64_t; using u64 = uint64_t;
using f32 = float_t; using f64 = double_t;
using usize = size_t;using str = string;
template <class T> using vec = vector<T>;
#define times(n, i) for (i32 i = 0; i < (n); i++)
#define range(n, m, i) for (u64 i = (n); i < (m); i++)
#define upto(n, m, i) for (i32 i = (n); i <= (m); i++)
#define downto(n, m, i) for (u64 i = (n); i >= (m); i--)
#define foreach(xs, x) for (auto &x : (xs))
#define all(xs) (xs).begin(), (xs).end()
#define sortall(xs) sort(all(xs))
#define reverseall(xs) reverse(all(xs))
#define uniqueall(xs) (xs).erase(unique(all(xs)), (xs).end())
#define maximum(xs) *max_element(all(xs))
#define minimum(xs) *min_element(all(xs))
const i64 MOD = 1000000007;

i64 check(i64 n) {
    if (n == 3 || n == 5)
        return -1;
    if (n % 2 == 0)
        return 2;
    if (n % 3 == 0)
        return 3;
    if (n % 5 == 0)
        return 5;
    usize i = 7; i32 b = 0;
    while (i <= i64(sqrt(n))) {
        if (n % i == 0)
            return i;
        if (b == 0)
            i += 4;
        else
            i += 2;
    }
    return -1;
}

i32 main()
{
    i64 L, H;
    cin >> L >> H;

    i64 p = 1;
    i64 ans = 1;
    i64 x = H;
    while (x > p*p && x >= L) {
        i64 c = check(x);
        if (c < 0) {
            x -= (p > 2 && (x % 2 == 1)) ? 2 : 1;
            continue;
        }
        if (p < c) {
            p = c;
            ans = x;
        }
        x -= (p > 2 && (x % 2 == 1)) ? 2 : 1;
    }

    cout << ans << endl;
    return 0;
}