//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static int tankvol(int h, int d, int vt)
        {
            int r = d/2;
            int h2 = d - h;
            double areaOfCircle = Math.PI * r * r;
            double areaOfSector = r * r * Math.Acos((double)(r - h2)/r);
            double areaOfTriangle = (r - h2) * Math.Sqrt(2 * r* h2 - h2 * h2);
            double areaOfLiquid = areaOfCircle - areaOfSector + areaOfTriangle;
            double l = vt/(Math.PI * r * r);
            return (int)Math.Floor(areaOfLiquid * l);
        }

        public static void Main(string[] args)
        {
            int a = tankvol(80,120,3500);
            Console.WriteLine(a);
        }
    }
}