C : Malloc ERROR [migrated]

I'm having trouble with MALLOC in C. I have the following code :

//This program finds the sum of two matrices using MALLOC 
#include<stdio.h>
#include<stdlib.h>
void main()
{
 int *a,i,r1,c1;
 printf("\nEnter the dimensions of the Matrix :");
 scanf("%d %d",&r1,&c1);
 if(r1==c1)
 {
  a=(int*)calloc(r1*r1,sizeof(int));
  b=(int*)calloc(r1*r1,sizeof(int));
  c=(int*)calloc(r1*r1,sizeof(int));
  printf("\nElements of A :");
  for(i=0;i<r1*c1;i++)
  {
   scanf("%d",&a[i]);
  }    printf("\nElements of A :");
  for(i=0;i<r1*c1;i++)
  {
   scanf("%d",&b[i]);
  }      
  for(i=0;i<r1*c1;i++)
  {
   c[i]=a[i]+b[i];
  }
  /***I'm not writing the remaining part ..It display the Matrix C ***/   
  free(a);
  free(b);
  free(c); 
 }
else
  printf("\nOnly Square Matrices \n");

}

This program find the sum of two matrices . When i run this program

 Enter the dimensions of the Matrix :3 3 

Enter the elements of Matrix A :1 2 3 4 5 6 7 8 9 
 10 11 12 1 3 5 45 4  6 6 46 4 6 64 6  64 64  6 6  64 64  6 64 
 //It doesn't stop till i press Ctrl+C 

I don't know why this happens . Help me figure out the exact problem .