עזרה בכתיבת תוכנית בשפת סי שארפ

אני אנסה לכתוב משהו

console.write("\ncorner elements sum = ");
console.write(arr[0, 0] + arr[0, m - 1] +
arr[n - 1, 0] +
arr[n - 1, m - 1]);
}

in a m by n array, where m is the number of rows and n is the number of columns, the array has these coordinates

upper left: 0,0
lower left: (m-1),0
upper right: 0,(n-1)
lower right: (m-1),(n-1)

the way i understand your assignment is to find the sum of those
so i tried to write you this before its the explaination i hoe i helped you