Matrix addition and multiplication program

Program:
#include<stdio.h>
 void main()
 {
 int ch,i,j,m,n,p,q,k,r1,c1,a[10][10],b[10][10],c[10][10];
 clrscr();
 printf("************************************");
 printf("\n\t\tMENU");
 printf("\n**********************************");
 printf("\n[1]ADDITION OF TWO MATRICES");
 printf("\n[2]MULTIPLICATION OF TWO MATRICES");
 printf("\n[0]EXIT");
 printf("\n**********************************");
 printf("\n\tEnter your choice:\n");
 scanf("%d",&ch);
 if(ch<=2 & ch>0)
 {
 printf("Valid Choice\n");
 }
 switch(ch)
 {
 case 1:
 printf("Input rows and columns of A & B Matrix:");
 scanf("%d%d",&r1,&c1);
 printf("Enter elements of matrix A:\n");
 for(i=0;i<r1;i++)
 {
 for(j=0;j<c1;j++)
 scanf("%d",&a[i][j]);
 }
 printf("Enter elements of matrix B:\n");
 for(i=0;i<r1;i++)
 {
 for(j=0;j<c1;j++)
 scanf("%d",&b[i][j]);
 }
 printf("\n =====Matrix Addition=====\n");
 for(i=0;i<r1;i++)
 {
 for(j=0;j<c1;j++)
 printf("%5d",a[i][j]+b[i][j]);
 printf("\n");
 }
 break;
 case 2:
 printf("Input rows and columns of A matrix:");
 scanf("%d%d",&m,&n);
 printf("Input rows and columns of B matrix:");
 scanf("%d%d",&p,&q);
 if(n==p)
 {
 printf("matrices can be multiplied\n");
 printf("resultant matrix is %d*%d\n",m,q);
 printf("Input A matrix\n");
 read_matrix(a,m,n);
 printf("Input B matrix\n");
 /*Function call to read the matrix*/
 read_matrix(b,p,q);
 /*Function for Multiplication of two matrices*/
 printf("\n =====Matrix Multiplication=====\n");
 for(i=0;i<m;++i)
 for(j=0;j<q;++j)
 {
 c[i][j]=0;
 for(k=0;k<n;++k)
 c[i][j]=c[i][j]+a[i][k]*b[k][j];
 }
 printf("Resultant of two matrices:\n");
 write_matrix(c,m,q);
 }
 /*end if*/
 else
 {
 printf("Matrices cannot be multiplied.");
 }
 /*end else*/
 break;
 case 0:
 printf("\n Choice Terminated");
 exit();
 break;
 default:
 printf("\n Invalid Choice");
 }
 getch();
 }
 /*Function read matrix*/
 int read_matrix(int a[10][10],int m,int n)
 {
 int i,j;
 for(i=0;i<m;i++)
 for(j=0;j<n;j++)
 scanf("%d",&a[i][j]);
 return 0;
 }
 /*Function to write the matrix*/
 int write_matrix(int a[10][10],int m,int n)
 {
 int i,j;
 for(i=0;i<m;i++)
 {
 for(j=0;j<n;j++)
 printf("%5d",a[i][j]);
 printf("\n");
 }
 return 0;
 }

Output: