#include <stdio.h>

int array_sum(int matrix[][3], int rows, int columns);

int main(void) {
  int sum;
  int a[2][3] = {{1, 2, 3}, {4, 5, 6}};

  sum = array_sum(a, 2, 3);
  printf("The sum is: %d\n", sum);
  
  return 0;
}

int array_sum(int matrix[][3], int rows, int columns){
  int i, j, sum = 0;;

  for (i = 0; i < rows; i++)
    for (j = 0; j < columns; j++)
      sum += matrix[i][j];  

  return sum;
}