危险行为请勿模仿

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
int a[100005];
int main(){
	cin.tie(nullptr) -> sync_with_stdio(0);
	cout.tie(nullptr) -> sync_with_stdio(0);
	int n;
	cin >> n;
	n++;
	int ans = log2(n);
	cout << (1ll << ans + ((n & (-n)) != n)) - 1;

	return 0;
}