import java.util.*;
class menu {
    public static void main(String args[]) {
        String choice = "";
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter your choice 'a' or 'b'");
        choice = sc.nextLine();
        switch (choice) {
            case "a":
                int i, j;
                for (i = 1; i <= 5; i++) {
                    for (j = 5; j >= i; j--) {
                        if ((i + j) % 2 == 0) {
                            System.out.print("1 ");
                        } else {
                            System.out.print("0 ");
                        }
                    }
                    System.out.println();
                }
                break;
            case "b":
                System.out.println("Enter 'n' th term");
                int sum = 0, f, s, n;
                n = sc.nextInt();
                for (f = 1; f <= n; f++) {
                    s = (f * f + 1);
                    sum += s;
                }
                System.out.print(sum);
                break;
            default:
                System.out.println("Wrong Choice");
        }
    }
}

int sgn = 1; 
for(f = 1; f <= n; f++)
{
    s = sgn * (f * f + 1);
    sum += s;
    sgn *= -1;
}