class Matrix:
 def __init__(self,numrows,numcolumns):
 #@param numrows : int
 #@param numcolumns : int
  self.row=numrows
  self.col=numcolumns
  self.mat=[]
  for i in range(0,numrows):
   self.mat.append([])
   for j in range(0,numcolumns):
    self.mat[i].append(0)

 def minor(self,j):
 #@ come riga di riferimento si prende i=0
 #@param j : int (colonna da cancellare)
 #@return matrix (minore ottenuto cancellando riga 0 e colonna j)
  if self.row > 2 :
   self.mat.remove(self.mat[0])
   for h in range (0,self.col-1):
    self.mat[h].pop(j)
    self.row=self.row-1
    self.col=self.col-1
  return self


 def det(self,D=0):                #@NOT WORKING
 #@ return int : determinante della matrice
  assert self.row==self.col
  if self.row==1:
   return self.mat[0]
  elif self.row==2:
   D=D+((self.mat[0][0]*self.mat[1][1])-(self.mat[0][1]*self.mat[1][0]))
   return D
  else:
  #@sviluppo di Laplace
   for j in range (0,self.row):
    D=D+(pow((-1.0),(j+2.0))*float(self.mat[0][j])*float(self.minor(j).det()))
   return D