diagonalSum(mat) {
        let totalSum = 0;  // Initialize the total sum
        let n = mat.length;
        // ToDo: Write Your Code Here.//[[5]]
        for(let i = 0; i < n ; i++){
            if(i !== n-i-1){
                totalSum+=(mat[i][i] + mat[i][n-1-i])
            }else{
                totalSum+=mat[i][i]
            }
        }
        return totalSum;  // Return the calculated total sum
    }