class MyMatrix:
    # Constructor - parameterized
    row = 0
    column = 0
    matrix = {}

    def __init__(self, list):
        self.row = len(list)
        self.column = len(list[0])
        test = len(list[0])
        for i in range(len(list)):
            if  len(list[i]) != test:
                raise Exception('Not a matrix')
        dictionary = {}
        for i in range(self.column):
            for j in range(self.row):
                if (list[i][j] == 0):
                   continue
                dictionary[i*self.column + j] = list[i][j]

        self.matrix = dictionary

    def __str__(self):
       for i in range((self.row) *(self.column)):
            if i % self.column == 0:
                print("|  ",end="")
            if i in self.matrix:
                print(f"{self.matrix[i]}    ",end="")
            else:
                print("0    ",end="")
            if i % self.column == self.column -1:
                print("|\n",end="")

    def __getitem__(self, packing):
        column2,row1 = packing
        if  column2 > self.column or row1 > self.row:
            raise Exception('Outside of Bounds')
        if column2*self.column + row1 in self.matrix:
            return self.matrix[column2*self.column + row1]
        else:
            return 0




m = [[3,0,-2,11],[0,0,9,0],[0,7,0,0],[0,0,0,-3]]
object = MyMatrix(m)
object.__str__()
#Wir haben keine Lösung mitm[0][0]= 3, da __getitem__ nur ein Argument nimmt
x = object[0,0]

print(x)