stochiometry = [  
  1  0  0  0  0  0  0  0 ;
  0  1  0  0  0  0  0  0 ;
  -1 0  1  0  0  0  0  0 ;
  -2 0  0  1  0  0  0  0 ;
  0  -2 0  1  0  0  0  0 ;
  0  -1 0  0  1  0  0  0 ;
  0  0  -1 0  0  0  0  0 ;
  0  0  0  -1 0  0  0  0 ;
  0  0  0  0  -1 0  0  0 ;
  0  0  -1 0  0  1  0  0 ;
  0  0  -2 0  0  0  1  0 ;
  0  0  -3 0  0  0  0  1 ;
  0  0  0  -2 0  1  0  0 ;
  0  0  0  -1 0  0  1  0 ;
  0  0  0  -2 0  0  0  1 ;
  0  0  0  0  -3 1  0  0 ;
  0  0  0  0  -2 0  1  0 ;
  0  0  0  0  -1 0  0  1 ;
  0  0  0  0  0  -1 0  0 ;
  0  0  0  0  0  0  -1 0 ;
  0  0  0  0  0  0  0  -1 ];
N = 8;
M = 21;
