I have issue in programming question

Create a class called 'Matrix' containing constructor that initializes the number of rows and the number of columns of a new Matrix object. The Matrix class has the following information:
1 - number of rows of matrix
2 - number of columns of matrix
3 - elements of matrix 
The Matrix class has functions for each of the following:
1 - get the number of rows
2 - get the number of columns
3 - set the elements of the matrix at a given position (i,j)
4 - adding two matrices.
5 - multiplying the two matrices
You can assume that the dimensions are correct for the multiplication and addition.

class Matrix:
    def __init__(self,l,k):
        self.row=l
        self.col=k
    def detail(self):
        matrix=[]
        for i in range(self.row):
            matrix.append([])
            for j in range(self.col):
                self.l=int(input("enter the element"))
                matrix[i].append(self.l)
        print(matrix)
    def col1(self):
        print("No of rows are:",self.row)
    def row1(self):
        print("No of col are:",self.col)
    def sum(self,m,n):
        self.c=m
        self.v=n
        matrix2=[]
        for i in range(self.row):
          for j in range(self.col):
            matrix2[i][j]=self.c[i][j]+self.v[i][j]
        return matrix2


row=int(input("Enter the no of row:"))
col=int(input("Enter the no of col:"))
m1=Matrix(row,col)
m2=Matrix(row,col)
m1.detail()
m1.col1()
m1.row1()
m3=m1.sum(m1,m2)
print(m2)

But it is giving error on 25th line that matrix object is not subscriptable