import std.stdio, std.conv, std.string, std.bigint;
import std.math, std.random, std.datetime;
import std.array, std.range, std.algorithm, std.container;
string read(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }

void main(){
	long l = read.to!long;
	long h = read.to!long;
	
	int pmax = 100_000;
//	if(h < 10_000) pmax = 100;
	
	debug writeln("pmax:", pmax);
	
	bool[] isCompound = new bool[](pmax);
	for(int i = 2; i < pmax; i ++){
		if(isCompound[i]) continue;
		for(int j = i + i; j < pmax; j += i){
			isCompound[j] = 1;
			}
		}
	debug writeln("isCompound[0 .. 20]:", isCompound[0 .. 20]);
	
	long[] xs = [];
	for(int p = 2; p < pmax; p ++){
		if(isCompound[p]) continue;
		if(p >= l) break;
		if(l <= (h / p) * p) xs ~= (h / p) * p;
		}
	
	xs.sort();
	debug writeln("xs:", xs);
	
	long[] ys;
	{
		long y = 0;
		foreach(x; xs) if(x != y) y = x, ys ~= y;
		}
	debug writeln("ys:", ys);
	
	long answer = 0;
	for(int p = 2; p < pmax; p ++){
		if(isCompound[p]) continue;
		foreach(i, y; ys) if(y % p == 0){
			answer = y;
			ys[i] = 1;
			debug writeln("p:", p, " answer:", answer);
			}
		}
	
	answer.writeln;
	}