只WA一个测试点

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ldb long double

ll n,k;
ll POW(ll a,int b){
	ll sum=1;
	while(b!=0){
		if(b&1==1) sum=sum*a;
		a*=a;
		b=b>>1;
	}
	return sum;
}

int main(){
	cin>>n>>k;
	ll a=floor(log2(n));
	//1152921504606846975  59=a
	//1000000000000000000
	//cout<<POW(2,40)<<" ";
	ll op=POW(2,a+1);
	if(k==1) cout<<n;
	else cout<<op-1;
	return 0;
}