Matrix Multiplication

 1. You are given a number n1, representing the number of rows of 1st matrix.

2. You are given a number m1, representing the number of columns of 1st matrix.
3. You are given n1*m1 numbers, representing elements of 2d array a1.
4. You are given a number n2, representing the number of rows of 2nd matrix.
5. You are given a number m2, representing the number of columns of 2nd matrix.
6. You are given n2*m2 numbers, representing elements of 2d array a2.
7. If the two arrays representing two matrices of dimensions n1 * m1 and n2 * m2 can be multiplied, display the contents of prd array as specified in output Format.
8. If the two arrays can't be multiplied, print "Invalid input".

Input Format

A number n1
A number m1
e11
e12..
e21
e22..
.. n1 * m1 number of elements of array a1
A number n2
A number m2
e11'
e12'..
e21'
e22'..
.. n2 * m2 number of elements of array a2

Output Format

e11' e12' e13' ..
e21' e22' e23' ..
.. elements of prd array

Constraints
1 <= n1 <= 10^2
1 <= m1 <= 10^2
-10^9 <= e11, e12, .. n1 * m1 elements <= 10^9
1 <= n2 <= 10^2
1 <= m2 <= 10^2
-10^9 <= e11', e12', .. n2 * m2 elements <= 10^9
Sample Input
2
3
10
0
0
0
20
0
3
4
1
0
1
0
0
1
1
2
1
1
0
0
Sample Output
10 0 10 0
0 20 20 40

import java.io.*;
import java.util.*;

public class Main{

public static void main(String[] args) throws Exception {
    // write your code here
    Scanner sc = new Scanner(System.in);
    int n1 = sc.nextInt();
    int m1 = sc.nextInt();
    int[][] A1 = new int[n1][m1];
    for(int i=0;i<n1;i++)
        for(int j=0;j<m1;j++)
            A1[i][j] = sc.nextInt();
            
    int n2 = sc.nextInt();
    int m2 = sc.nextInt();
    int[][] A2 = new int[n2][m2];
    for(int i=0;i<n2;i++)
        for(int j=0;j<m2;j++)
            A2[i][j] = sc.nextInt();
            
    if(m1 == n2){
        int[][] A = new int[n1][m2];
        
        for(int i=0;i<n1;i++){
            for(int j=0;j<m2;j++){
                int sum = 0;
                for(int k=0;k<m1;k++){
                    sum += A1[i][k]*A2[k][j];
                }
                A[i][j] = sum;
            }    
        }
        
        for(int i=0;i<n1;i++){
            for(int j=0;j<m2;j++)
                System.out.print(A[i][j]+" ");
            System.out.println();
        }
    } 
    else 
        System.out.println("Invalid input");
    
 }

}