C program to find the sum and difference of the matrixs

/* Write a C program to accept two matrices and find the sum and difference of the matrices  */

#include <stdio.h>
#include <stdlib.h>

int A[10][10], B[10][10], sumat[10][10], diffmat[10][10];
int i, j, R1, C1, R2, C2;

void main()
{

/* Function declarations */
    void readmatA();
void printmatA();
    void readmatB();
void printmatB();
void sum();
    void diff();

printf("Enter the order of the matrix A\n");
    scanf("%d %d", &R1, &C1);

printf("Enter the order of the matrix B\n");
scanf("%d %d", &R2,&C2);

if( R1 != R2 && C1 != C2)
{
 printf("Addition and subtraction are possible\n");
 exit(1);
}
else
{
      printf("Enter the elements of matrix A\n");
readmatA();
printf("MATRIX A is\n");
printmatA();

      printf("Enter the elements of matrix B\n");
readmatB();
      printf("MATRIX B is\n");
      printmatB();

      sum();
      diff();
}
} /* main() */

/* Function to read a matrix A */
void readmatA()
{
for(i=0; i<R1; i++)
      {
for(j=0; j<C1; j++)
{
scanf("%d",&A[i][j]);
}
}
      return;
}

/* Function to read a matrix B */
void readmatB()
{
for(i=0; i<R2; i++)
      {
for(j=0; j<C2; j++)
{
scanf("%d",&B[i][j]);
}
      }
}

/* Function to print a matrix A */
void printmatA()
{
      for(i=0; i<R1; i++)
      {
for(j=0; j<C1; j++)
{
printf("%3d",A[i][j]);
}
printf("\n");
}
}

/* Function to print a matrix B */
void printmatB()
{
      for(i=0; i<R2; i++)
      {
for(j=0; j<C2; j++)
{
printf("%3d",B[i][j]);
}
printf("\n");
      }
}
/*Function to find the sum of elements of matrix A and Matrix B*/
void sum()
{
    for(i=0; i<R1; i++)
    {
for(j=0; j<C2; j++)
        {
sumat[i][j] = A[i][j] + B[i][j];
}
     }
     printf("Sum matrix is\n");
     for(i=0; i<R1; i++)
     {
for(j=0; j<C2; j++)
        {
printf("%3d",sumat[i][j]) ;
}
printf("\n");
     }
     return;
}

/*Function to find the difference of elements of matrix A and Matrix B*/
void diff()
{
    for(i=0; i<R1; i++)
    {
for(j=0; j<C2; j++)
        {
diffmat[i][j] = A[i][j] - B[i][j];
}
     }
   
     printf("Difference matrix is\n");
     for(i=0; i<R1; i++)
      {
       for(j=0; j<C2; j++)
       {
printf("%3d",diffmat[i][j]);
       }
       printf("\n");
     }
 return;
}

/*---------------------------------------------------
Output
Enter the order of the matrix A
2 2
Enter the order of the matrix B
2 2
Enter the elements of matrix A
1
2
3
4
MATRIX A is
  1  2
  3  4
Enter the elements of matrix B
2
4
6
8
MATRIX B is
  2  4
  6  8
Sum matrix is
  3  6
  9 12
Difference matrix is
 -1 -2
 -3 -4
-----------------------------------------------------*/