#include <iostream>
#include <stdint.h>

using namespace std;

int main()
{
    uint32_t L, R, M;
    cin >> L >> R;
    M = L^R;

    M--;
    M |= M >> 1;
    M |= M >> 2;
    M |= M >> 4;
    M |= M >> 8;
    M |= M >> 16;

    cout << M;

    return 0;
}