using System;

public class Program
{

    public static int factorial(int n) {
        if (n == 1) return 1;
        return n * factorial(n-1);
    }

    public static int division(int a, int b) {
        if (a < b) return (b-a) == 0 ? 1 : 0;
        return 1 + division(a-b, b);
    }

    public static int mod(int a, int b) {
        if (a < b) return a;
        return mod(a-b, b);
    }

    public static bool multip(int a, int b) {
        if (a < b) return a == 0;
        return multip(a-b, b);
    }

    public static int sum(int n) {
        if (n == 1) return 1;
        return n + sum(n-1);
    }

    public static int odd_mult_sum(int n) {
        if (n % 2 == 0) return odd_mult_sum(n-1);
        if (n == 1) return 1;
        return n * odd_mult_sum(n-2);
    }

    public static int complex_sum(int n) {
        if (n % 2 == 0) return n*n + complex_sum(n-1);
        if (n == 1) return 2;
        return n*2 + complex_sum(n-1);
    }

    public static int series_n(int n) {
        if (n == 1) return 1;
        return 2 + series_n(n-1);
    }

    public static int sum_n(int n) {
        if (n == 1) return 1;
        return series_n(n) + sum_n(n-1);
    }

    public static int series_n_1(int n) {
        if (n == 1) return 0;
        return (n-1) + series_n_1(n-1);
    }

    public static int sum_n_1(int n) {
        if (n == 1) return 0;
        return series_n_1(n) + sum_n_1(n-1);
    }



    public static void Main()
    {

    }
}