increment element of 2D matrix by 2 times

#include <stdio.h>
    	void main()
    	{
 
       	 int i, j, r, c, a[50][50];
       
printf("Enter the number of rows and columns of matrix:");
         scanf("%d%d",&r,&c);
                   
         printf("Enter the elements of matrix:");
         for(i = 0; i < r; i++)
         for(j = 0; j < c; j++)
            {
            scanf("%d",&a[i][j]);
            }

        for (i = 0; i < r; i++)
        for (j = 0; j <c ; j++)
        {
        a[i][j] = a[i][j] + 2*(a[i][j]);
        
        printf("%d\n",a[i][j]);
        }
 
        }