#include <iostream>

using namespace std;

int m, n;

int main() {
    while (cin >> m >> n) {
        if (n == 0 && m == 0) break;
        long long l = 2 * m;
        long long r = 2 * m + 1;
        int res = 1;
        int level = 1; //每一层有多少个结点
        while (r <= n) { //边界条件
            level *= 2;
            res += level;
            l = l * 2;
            r = r * 2 + 1;
        }
        if (l <= n) res = res + n - l + 1; //加上最后一层结点
        cout << res << endl;
    }
    return 0;
}