A C# folder exercice ,im beginer explain me pls

Question

A store sells N models of mobile phones. The data on the number of phones of each model sold during the year are stored in the two-dimensional T-array with N lines and 12 columns. The value of T and i represents the number of (i)) sold in month ((j)).

Task

Write a program that will calculate the total number of phones sold during the year and the phone model from which no copies have been sold. The program must contain a subprogram with the name NT. The NT program receives as a parameter the whole value (((i))) - the indentation of a T-line and returns an integer value - the sum of the elements in the line ((i)) of the T . Input ::: The TEL.IN file contains a whole number N-number of marketed mobile models (1 <= N <= 100). Count N lines containing 12 integers separated by space - the elements of the T-array. The number with the index j in the line i + 1 of the file is the value of the element T [i, j] (T [i, j <100]).

Output

The TEL.OUT file contains two lines. The first line contains a whole number - the total number of phones sold during the year. The second line contains whole numbers separated by space - the index of the models of mobile phones that have not been sold If there are no such models, then the second line contains the expression: Are not.