Migrated from Lutece 2844 Senpai and Pascal

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Description

Kanade regards Pascal users as her senpais. Because all her senpais use Pascal. Although she is a C++ user.

One day, she was confused by a problem. Finally, she found the code which had passed this problem written by her senpai. Of course, this code is written by Pascal.

program calc;

var
	i, j, l, r, ans: int64;

begin
	ans := 0;
	read(l);
	read(r);
	i := l;
	while i <= r do begin
		j := l;
		while j <= r do begin
			if (i or j) > ans then
				ans := i or j;
			inc(j);
		end;
		inc(i);
	end;
	writeln(ans);
end.

Some facts in Pascal which may be useful:

• i or j means the bitwise OR of $i$ and $j$;
• inc(x) means $x\leftarrow x+1$, and it's the same as ++x in C++;
• read(x) means read $x$ from the standard input, writeln(x) means write $x$ to the standard output (and a newline, but it's not important);
• int64 in Pascal is same as long long in C++.

Because of the weak data, the code passed all the test cases. Kanade made some stronger data, but she didn't know whether these data is valid. Please write a program that outputs the same answer for the same input as the Pascal code will. So that Kanade can check her code.

Input

There is only one line in the input. The first line contains two integer $l,r\ (1\le l\le r\le 10^{18})$.

Output

Output one integer in a line, indicating the answer which the Pascal code will output.

Samples

114 514

1023

Resources

The 18th UESTC Programming Contest Preliminary