function hourglassSum(arr) {
  let sum = -Infinity;

  for (let i = 0; i <= 3; i++) {
    for (let j = 0; j <= 3; j++) {
      let a = arr[i][j];
      let b = arr[i][j + 1];
      let c = arr[i][j + 2];

      let d = arr[i + 1][j + 1];

      let e = arr[i + 2][j];
      let f = arr[i + 2][j + 1];
      let g = arr[i + 2][j + 2];

      if (a + b + c + d + e + f + g > sum) {
        sum = a + b + c + d + e + f + g;
      }
    }
  }
  return sum;
}