#include <algorithm>
#include <iostream>
#include <vector>
typedef std::vector<int>::iterator VECINT_ITER;
int Josephus(int n, int k)
{ 
static std::vector<int> vecJosephus(1, 0); 
if (n <= (int)vecJosephus.size())     
return vecJosephus[n - 1];
int j = (Josephus(n - 1, k) + k) % n;
vecJosephus.push_back(j);
return j;
}
int main(void)
{
for (int i = 0; i < 100000; Josephus(++i, 15));
for (int nSizeMin, nSizeMax; std::cin >> nSizeMin >> nSizeMax;) 
{
if (nSizeMin > nSizeMax)           
std::swap(nSizeMin, nSizeMax);        
if (nSizeMin == 0 && nSizeMax == 0)          
break;        
std::vector<int> vecCover(nSizeMin / 2, 0);     
for (int nSize = nSizeMin, nJump = 15; nSize <= nSizeMax; ++nSize) {          
int j = Josephus(nSize, nJump);        
if (j > nSize / 2)              
j = nSize - j;          
if (j < vecCover.size())            
vecCover[j] = 1;   
}  
VECINT_ITER ir = std::find(vecCover.begin() + 1, vecCover.end(), 0);     
if (ir == vecCover.end())        
std::cout << "Better estimate needed" << std::endl;   
else       
std::cout << ir - vecCover.begin() << std::endl; 
}
return 0;
}