Hackerrank Maximising xor

/**
 *    author:  compounding
 *    created: 2024-11-12 20:08:38
 **/
#include <bits/stdc++.h>
using namespace std;
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
#define NeedForSpeed                  \
    ios_base::sync_with_stdio(false); \
    cin.tie(NULL);                    \
    cout.tie(NULL);
#define int long long
#define all(x) (x).begin(), (x).end()
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<vi> vvi;
typedef vector<pair<int, int>> vpi;
#define f first
#define s second
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define endl "\n"
const int mod = 1000000007;
int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); }
void solve()
{
    int l, r;
    cin >> l >> r;
    // we have to find the maximum value of (x^y) where l <= x <= y <= r
    // observe the msb of l^r is always fixed, we can fill all other bits as 1
    int s = l ^ r;
    int ans = 1;
    while (s)
    {
        s >>= 1;
        ans <<= 1;
    }
    // 2^msb - 1
    cout << ans - 1 << endl;
    return;
}

signed main()
{
    NeedForSpeed;
    int t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
    }
    return 0;
}