// Write a program that inputs positive integer n and prints squares from 1 to n*n

// The program can use only + and – operations on integers and total number of such

// operations should be proportional to n.

using System;

public class Program

{

    public static void Main()

    {

        Console.Write("Enter the value of n: ");

        int n = Convert.ToInt32(Console.ReadLine());

        int k = 0;

        int k2 = 0;

        // invariant: all squares from 1 to k are printed

        //            and k2 = k*k and k <=n

        while (k != n)

        {

            // k < n

            k++;

            // k2 = (k-1)(k-1) = k*k - 2k - 1 and k<=n

            k2 = k2 + k + k - 1;

            // k2 = k*k

            // all squares from 1 to k-1 are printed and k<=n

            Console.WriteLine("Square of {0} is {1}", k, k2);

            // all squares from 1 to k are printed and k<=n

        }

        // invariant: all squares from 1 to n are printed

​

        // Time = O(n)

    }

}