Problem 1 - Math Expression

//Problem 3 – Trapezoid
//Write a program that prints on the console the border of a trapezoid by given number N.
//The width of the top side of the trapezoid must be exactly N.
//The width of the bottom side of the trapezoid must be exactly 2 * N.
//The height of the trapezoid must be exactly N + 1.
//Also the top right and the bottom right angle of the trapezoid must be equal to 90 degrees.
//See the examples bellow.
//Input
//The input data is being read from the console.
//On the only line in the console you are given an integer number N, showing the width of the smallest trapezoid side.
//The input data will always be valid and in the format described. There is no need to check it explicitly.
//Output
//The output data must be printed on the console.
//You must write the border of the described trapezoid on the console.
//Use the symbol “*” (asterisk) to mark the border of the trapezoid.
//Use the symbol “.” (dot) to illustrate the empty spaces outside and inside the trapezoid.
//Constraints
//•   The number N is a positive integer between 3 and 39, inclusive.
//•   Allowed working time for your program: 0.25 seconds.
//•   Allowed memory: 16 MB.

using System;

class Program
{
    static void Main()
    {
        decimal n = decimal.Parse(Console.ReadLine());
        decimal m = decimal.Parse(Console.ReadLine());
        decimal p = decimal.Parse(Console.ReadLine());
        double mod = Math.Truncate((double)m % 180);

        decimal first = (n*n) + (1/ (m*p) + 1337);
        decimal second = n - (128.523123123M * p);
        decimal third = (decimal)Math.Sin(mod);
        Console.WriteLine(Math.Round(((first/second) + third), 6));
    }
}