class Matrix(object):
    '''Matrix real numbers'''
    def __init__(self,h,w):
        self._nrows=h
        self._ncols=w
        self._data=[0]*(self._nrows*self._ncols)
    def __str__(self):
        return "Matrix:"+str(self._nrows)+"by"+str(self._ncols)
    def setnrows(self,w):
        self._nrows=w
        self.reinit()
    def getnrows(self):
        return self._nrows
    def getncols(self):
        return self._ncols
    def reinit(self):
        self._data=[0]*(self._nrows*self._ncols)
    def setncols(self,h):
        self._ncols=h
        self.reinit()
    def setValue(self,i,j,value):
        if i<self._nrows and j<self._ncols:
            self._data[i*self._nrows+j]=value
        else:
            raise Exception ("Ошибка")
    def multiply(self,otherMatrix):
        result=Matrix(self._nrows,otherMatrix.getncols())
        return result
    def inv (self):
        if self._ncols !=self._nrows: raise Exception("Данная матрица не квадратная")
        invertedMatrix=Matrix(self._ncols,self._nrows)
        invertedMatrix.setncols(self._ncols)
        invertedMatrix.setnrows(self._nrows)
        return invertedMatrix
class SparseMatrix(Matrix):
    def __str__ (self):
        return "SparseMatrix:"+str (self._nrows)+"by" +str (self._ncols)
    def reinit(self):
        self._data={}
    def setValue(self,i,j,value):
        self._data[(i,j)]=value
    def multiply(self,otherMatrix):
        result=SparseMatrix(self._nrows,otherMatrix.getncols())
        return result
    def inv(self):
        if self._ncols !=self._nrows:
            raise Exception("Данная матрица не квадратная")
        invertedMatrix=SparseMatrix(self._ncols,self._nrows)