Problem:
Score : 100 points

Problem Statement

Given is an integer r.

How many times is the area of a circle of radius r larger than the area of a circle of radius 1?

It can be proved that the answer is always an integer under the constraints given.

Constraints

1 \leq r \leq 100

All values in input are integers.

Input

Input is given from Standard Input in the following format:

r

Output

Print the area of a circle of radius r, divided by the area of a circle of radius 1, as an integer.

Sample Input 1

2

Sample Output 1

4

The area of a circle of radius 2 is 4 times larger than the area of a circle of radius 1.

Note that output must be an integer - for example, 4.0 will not be accepted.

Sample Input 2

100

Sample Output 2

10000

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

// ReSharper disable ArrangeTypeMemberModifiers
// ReSharper disable ConvertIfStatementToSwitchStatement
// ReSharper disable FunctionRecursiveOnAllPaths
// ReSharper disable InconsistentNaming
// ReSharper disable InlineOutVariableDeclaration
// ReSharper disable InvertIf
// ReSharper disable JoinDeclarationAndInitializer
// ReSharper disable MemberCanBeMadeStatic.Global
// ReSharper disable MemberCanBeMadeStatic.Local
// ReSharper disable NonReadonlyMemberInGetHashCode
// ReSharper disable PossibleNullReferenceException
// ReSharper disable RedundantUsingDirective
// ReSharper disable SuggestVarOrType_BuiltInTypes
// ReSharper disable SuggestVarOrType_Elsewhere
// ReSharper disable TailRecursiveCall
// ReSharper disable UnusedMember.Global
// ReSharper disable UnusedMember.Local
// ReSharper disable UseObjectOrCollectionInitializert

#if true && UTAKA_LOCAL

//#if false
#define UTAKA_DEBUG
#endif

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Numerics;
using System.Runtime.InteropServices;

namespace UtakaApp
{
    public partial class Program
    {
        //=========================================================================================
        // Answer
        //=========================================================================================

        public const string SiteName    = "AtCoder";
        public const string ContestName = "abc145";
        public const string ProblemName = "A";

        public void Solve()
        {
            int r = cin.ReadInt;
            cou.WriteLine(r * r);
        }
    }


//=========================================================================================
// Debug IO
//=========================================================================================

    public partial class Program
    {
        //=========================================================================================
        // Main
        //=========================================================================================

        private readonly ConsoleInput cin;
        private readonly IConsole     cou;

        public Program(ConsoleInput cin, IConsole cou)
        {
            this.cin = cin;
            this.cou = cou;
        }

        public static void Main(string[] args)
        {
#if UTAKA_LOCAL
//#if false
            new TestCaseCheckerForAtCoder().TestProblems();
#else
            var cin = new ConsoleInput(System.Console.In);
            var console = new MyConsole();
            new Program(cin, console).Solve();
            console.Flush();
#endif
        }

        //=========================================================================================
        // Library
        //=========================================================================================

        /// <summary>
        /// 要素数 (a, b) の、defaultValue で満たされた配列を作成します。
        /// </summary>
        /// <typeparam name="T">配列の型</typeparam>
        /// <param name="a">1次元の要素数</param>
        /// <param name="b">2次元の要素数</param>
        /// <param name="defaultValue">デフォルト値</param>
        /// <returns>指定した条件で初期化された配列</returns>
        public static T[,] Array2D<T>(int a, int b, T defaultValue)
            where T : struct
        {
            var ret = new T[a, b];
            for (int i = 0; i < a; i++)
            {
                for (int j = 0; j < b; j++)
                {
                    ret[i, j] = defaultValue;
                }
            }

            return ret;
        }

        /// <summary>
        /// 要素数 (a, b) のdefault値で満たされた配列を作成します。
        /// </summary>
        /// <typeparam name="T">配列の型</typeparam>
        /// <param name="a">1次元の要素数</param>
        /// <param name="b">2次元の要素数</param>
        /// <returns>初期化された配列</returns>
        public static T[,] Array2D<T>(int a, int b)
            where T : struct
        {
            var ret = new T[a, b];
            return ret;
        }

        /// <summary>
        /// 要素数 (a, b) の、defaultValue で満たされたJag配列を作成します。
        /// </summary>
        /// <typeparam name="T">配列の型</typeparam>
        /// <param name="a">1次元の要素数</param>
        /// <param name="b">2次元の要素数</param>
        /// <param name="defaultValue">デフォルト値</param>
        /// <returns>指定した条件で初期化された配列</returns>
        public static T[][] JagArray2D<T>(int a, int b, T defaultValue)
            where T : struct
        {
            var ret = new T[a][];
            for (int i = 0; i < a; i++)
            {
                ret[i] = Enumerable.Repeat(defaultValue, b).ToArray();
            }

            return ret;
        }

        /// <summary>
        /// 要素数 (a, b) のdefault値で満たされたJag配列を作成します。
        /// </summary>
        /// <typeparam name="T">配列の型</typeparam>
        /// <param name="a">1次元の要素数</param>
        /// <param name="b">2次元の要素数</param>
        /// <returns>初期化された配列</returns>
        public static T[][] JagArray2D<T>(int a, int b)
            where T : struct
        {
            var ret = new T[a][];
            for (int i = 0; i < a; i++)
            {
                ret[i] = new T[b];
            }

            return ret;
        }

        /// <summary>
        /// ジャグ配列をコピーして返す。
        /// </summary>
        public static T[][] CopyJagArray<T>(T[][] source)
            where T : struct
        {
            int   len  = source.Length;
            T[][] dest = new T[len][];

            for (int i = 0; i < len; i++)
            {
                T[] inner       = source[i];
                int innerLength = inner.Length;
                T[] newer       = new T[innerLength];
                Array.Copy(inner, newer, innerLength);
                dest[i] = newer;
            }

            return dest;
        }
    }

    public class ConsoleInput
    {
        private readonly char          _separator = ' ';
        private readonly TextReader    _stream;
        private readonly Queue<string> inputStream;

        public ConsoleInput(TextReader stream, char separator = ' ')
        {
            _separator  = separator;
            _stream     = stream;
            inputStream = new Queue<string>();
        }

        public string Read
        {
            get
            {
                if (inputStream.Count != 0)
                {
                    return inputStream.Dequeue();
                }

                var tmp = _stream.ReadLine().Split(_separator);
                for (var i = 0; i < tmp.Length; ++i)
                {
                    inputStream.Enqueue(tmp[i]);
                }

                return inputStream.Dequeue();
            }
        }

        public string ReadLine   => _stream.ReadLine();
        public int    ReadInt    => int.Parse(Read);
        public long   ReadLong   => long.Parse(Read);
        public double ReadDouble => double.Parse(Read);

        public string[] ReadStrArray(long N)
        {
            var ret = new string[N];
            for (long i = 0; i < N; ++i)
            {
                ret[i] = Read;
            }

            return ret;
        }

        public int[] ReadIntArray(long N)
        {
            var ret = new int[N];
            for (long i = 0; i < N; ++i)
            {
                ret[i] = ReadInt;
            }

            return ret;
        }

        public long[] ReadLongArray(long N)
        {
            var ret = new long[N];
            for (long i = 0; i < N; ++i)
            {
                ret[i] = ReadLong;
            }

            return ret;
        }
    }

    public interface IConsole
    {
        void Flush();
        void Write(object obj);
        void Write(string str);
        void WriteLine(object obj);
        void WriteLine(string str);
        void WriteLine();
    }

    public class MyConsole : IConsole
    {
        public MyConsole()
        {
            var sw = new StreamWriter(Console.OpenStandardOutput()) {AutoFlush = false};
            Console.SetOut(sw);
        }

        public void Flush()
        {
            Console.Out.Flush();
        }

        public void Write(object obj)
        {
            Write(obj.ToString());
        }

        public void Write(string str)
        {
            Console.Write(str);
        }

        public void WriteLine(object obj)
        {
            WriteLine(obj.ToString());
        }

        public void WriteLine(string str)
        {
            Console.WriteLine(str);
        }

        public void WriteLine()
        {
            Console.WriteLine();
        }
    }

#if UTAKA_LOCAL

    public class DebugConsole : IConsole
    {
        private readonly StringBuilder mSb;

        public DebugConsole()
        {
            mSb = new StringBuilder();
        }

        public void Flush()
        {
            // 何もしない
        }

        public void Write(object obj)
        {
            Write(obj.ToString());
        }

        public void Write(string str)
        {
            mSb.Append(str);
        }

        public void WriteLine(object obj)
        {
            WriteLine(obj.ToString());
        }

        public void WriteLine(string str)
        {
            mSb.AppendLine(str);
        }

        public void WriteLine()
        {
            mSb.AppendLine();
        }

        public string GetAllOutput()
        {
            return mSb.ToString();
        }
    }

#endif

#if UTAKA_LOCAL

    public class TestCaseCheckerForAtCoder
    {
        private string GetDirectoryPath()
        {
            var problemPart = string.IsNullOrEmpty(Program.ProblemName)
                ? ""
                : $"/{Program.ProblemName}";

            return
                $"{Environment.GetFolderPath(Environment.SpecialFolder.UserProfile)}/AlgorithmPrac/{Program.SiteName}/{Program.ContestName}{problemPart}";
        }

        private string GetInputFilePath(int testCaseNumber)
        {
            return $"{GetDirectoryPath()}/sample-{testCaseNumber}.in";
        }

        private string GetOutputFilePath(int testCaseNumber)
        {
            return $"{GetDirectoryPath()}/sample-{testCaseNumber}.out";
        }

        public bool TestProblem(int testCaseNumber)
        {
            var inputFilePath  = GetInputFilePath(testCaseNumber);
            var outputFilePath = GetOutputFilePath(testCaseNumber);

            TextReader inputStream = new StreamReader(inputFilePath);
            var        cin         = new ConsoleInput(inputStream);

            var debugConsoleWriter = new DebugConsole();

            new Program(cin, debugConsoleWriter).Solve();

            var output = debugConsoleWriter.GetAllOutput();

            TextReader outputStream = new StreamReader(outputFilePath);
            var        outputAnswer = outputStream.ReadToEnd();

            Dbg.WriteLine(output);
            Dbg.WriteLine(outputAnswer);

            var isCorrect = output == outputAnswer;

            return isCorrect;
        }

        public void TestProblems(int targetTestCaseNumber = -1)
        {
            if (targetTestCaseNumber >= 0)
            {
                Console.WriteLine($"!!!!!!!!!!!! Check TestCase {targetTestCaseNumber} !!!!!!!!!!");
            }

            bool isSuccessAll = true;

            int testCaseNumber = 0;
            while (true)
            {
                testCaseNumber++;

                if (targetTestCaseNumber >= 0 && targetTestCaseNumber != testCaseNumber)
                {
                    continue;
                }

                var inputFileName = GetInputFilePath(testCaseNumber);
                if (!File.Exists(inputFileName))
                {
                    break;
                }

                Console.WriteLine($"TestCase {testCaseNumber} =====================================================");

                var result = TestProblem(testCaseNumber);

                if (result)
                {
                    Console.WriteLine("Success");
                }
                else
                {
                    isSuccessAll = false;
                    Console.WriteLine("Failure *****");
                }
            }

            if (isSuccessAll)
            {
                Console.WriteLine("!!!!!!!!! All Success !!!!!!!!!");
            }
        }
    }

#endif

#if UTAKA_LOCAL

    public static class Dbg
    {
        public static void WriteLine(string str)
        {
            Console.WriteLine(str);
        }

        public static void Write(string str)
        {
            Console.Write(str);
        }
    }
#else
    public static class Dbg
    {
        public static void WriteLine(string str)
        {
        }

        public static void Write(string str)
        {
        }
    }

#endif
}