PROGRAMMING:Multiplication of matrix

A matrix in linear algebra can be expressed as a two-dimensional array of row * column. When both row and column are 1, it degenerates to a number. When row is 1, it is a row vector. When column is 1, it is a column vector.
Establish an integer matrix class matrix, and its private data members are as follows:
```
int row;
int column;
int **mat;
```
The matrix constructor of the integer matrix class is established;
An operator overload of * (multiplication sign) is established to facilitate multiplication of two input matrices;
Set up the output function void display() to output the integer matrix in column alignment by row. The formatted output statement is as follows:
```
cout<//Include < iomanip > is required
```
The main function defines three integer matrix class objects M1, M2 and M3
###Input format:
Input two matrices, M1 and M2, respectively.
Each matrix input is as follows:
Two integers R C in the first row give the number of rows and columns of the matrix respectively
Next, enter r rows, corresponding to each row of the integer matrix
Enter C integers for each row, and select the corresponding C column elements
###Output format:
The integer matrix is output after column alignment (width is 10) by row
Determine whether M1 and M2 can perform matrix multiplication.
If you can, after m3 = M1 * M2 operation, call the display function to output m3.
If not, output "invalid matrix multiplication!"
Tip: the input or output integer matrix must satisfy row > = 1 and column > = 1.
###Input example:
```in
4 5
1 0 0 0 5
0 2 0 0 0
0 0 3 0 0
0 0 0 4 0
5 5
1 2 3 4 5
2 3 4 5 6
3 4 5 6 7
4 5 6 8 9
5 6 7 8 9
```
###Output example:
```out
26 32 38 44 50
4 6 8 10 12
9 12 15 18 21
16 20 24 32 36
```






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