function hourglassSum(arr) {
    let max = -63;

    for (let i = 0; i < 4; i++) {
        for (let j = 0; j < 4; j++) {
            let sum = arr[i + 1][j + 1];
            for (let k = 0; k < 3; k++) {
                sum += arr[i][j + k];
                sum += arr[i + 2][j + k]
            }
            if (sum > max) max = sum;
        }
    }

    return max;
}