// @BEGIN_OF_SOURCE_CODE

/* @JUDGE_ID:  17243NT  180  C++  "Simulation" */

// Send to judge@uva.es

#include <iostream.h>
#include <fstream.h>
#include <iomanip.h>

#ifdef ONLINE_JUDGE
	#define ins cin
	#define outs cout
#else
	#define ins fin
	#define outs fout
	ifstream fin("myprog.in");
	ofstream fout("myprog.out");
#endif

int winnerccw(int ntotal);
int winnercw(int ntotal);

int main() {
	int i, nmin, nmax;
	int ccw[510], cw[510];

	for(i = 0; i <= 500; i++) {
		ccw[i] = winnerccw(i);
		cw[i] = winnercw(i);
	}
	
	while(ins >> nmin >> nmax) {
		bool win[510];
		
		if(nmin == 0 || nmax == 0) break;
		
		for(i = 0; i <= nmax; i++)
			win[i] = false;
		
		for(i = nmin; i <= nmax; i++) {
			win[ccw[i]] = true;
			win[cw[i]] = true;
		}
		
		for(i = 1; i <= nmin / 2; i++)
			if(!win[i]) break;
		
		if(i > nmin / 2)
			outs << "Better estimate needed\n";
		else outs << i << endl;
	}

	return 0;
}

int winnerccw(int ntotal) {
	int i, j, cur, next;
	int eeny[510];

	next = 0;
	for(i = 0; i < ntotal; i++)
		eeny[i] = i;

	for(i = ntotal; i > 0; i--) {
		next = (next + 14) % i;

		cur = eeny[next];

		for(j = next + 1; j < i; j++)
			eeny[j - 1] = eeny[j];
	}
	
	return cur;
}

int winnercw(int ntotal) {
	int i, j, cur, next;
	int eeny[510];
	
	next = 0;
	eeny[0] = 0;
	for(i = 1; i < ntotal; i++)
		eeny[i] = ntotal - i;
	
	for(i = ntotal; i > 0; i--) {
		next = (next + 14) % i;
		
		cur = eeny[next];
		
		for(j = next + 1; j < i; j++)
			eeny[j - 1] = eeny[j];
	}
	
	return cur;
}

// @END_OF_SOURCE_CODE