//↓円錐の体積を求める↓
class Frustum{ 
        double l = Math.PI;
        double vol(double r,double h){ //円柱の体積を求めるメソッド
            return(r*r*h*this.l/3);
        }
    }

//↓球体の体積を求める↓
class Sphere extends Frustum{ //クラスFrustumを継承 
        double vol(double r){   //Frustumクラスのメソッドをオーバーライド
            return (r*r*r*super.l*4/3);
        }
    }

//↓三角柱の体積を求める↓
class Prism extends Frustum{   //クラスFustumを継承
    public double vol(double r,double h,double l){  //Frustumクラスのメソッドをオーバーライド
        return (r*h*l/2);
        }
    }
class Total extends Frustum{
      public static void main(String args[]){ 
            Sphere  VS = new Sphere();  //Sphereオブジェクトを作成
            Frustum VF = new Frustum(); //Frustumオブジェクトを作成
            Prism   VP = new Prism();   //Prismオブジェクトを作成
            System.out.print("半径10\nの球体の体積");
            System.out.println("  = "+VS.vol(10));
            System.out.print("半径10\n高さ20\nの円錐の体積");
            System.out.println("  = "+VF.vol(10,20));
            System.out.print("底辺10\n縦15\n高さ20\nの三角柱の体積");
            System.out.println("  = "+VP.vol(10,15,20));
    }
}

//↓円の外周を求める↓
class Circumference{
    double circumference(double r){
        return(2*r*Math.PI);
        }
    double circumference2(double r){
        return(2*r*Math.PI);
        }
    }
//↓円の面積を求める↓
class Surface extends Circumference{
    double surface(double r){
        return(r*r*Math.PI);
        }
    double surface2(double r){
        return(r*r*Math.PI);
    }
}

class Menseki extends Circumference{
    double surface(double r){//球体の表面積を求めるクラス
        return(4*r*r*r*Math.PI);
        }
    public static void main(String args[]){
    Circumference a = new Circumference();
    Surface b = new Surface();
    Menseki c = new Menseki();
    double SS = (b.surface2(20)*(a.circumference(10)/a.circumference2(20))+(b.surface(10)));
    System.out.print("半径10\n母線20\nの表面積="+SS+"\n\n");
    System.out.print("半径10\nの球体の表面積="+c.surface(10)+"\n");
    }
}

import java.io.*;

class factrial {

  public static void main(String args[]) throws Exception {

    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    System.out.print("input natural number: ");
    int num = (new Integer(in.readLine())).intValue();

    System.out.print("for文を使った階乗計算      => ");
    System.out.println(num + "! =" + factfor(num));

    System.out.print("再帰呼び出しによる階乗計算 => ");
    System.out.println(num + "! =" + factrec(num));

  }

  /* for 文を使った階乗の計算 */
  static int factfor(int number) {

    int factrial = 1;

    for (int i = 1; i <= number; i++) {
      factrial = i * factrial;
    }

    return(factrial);

  }

  /* 再帰による階乗の計算 */
  static int factrec(int number) {
    if (number==0) return(1);
    return(number * factrec(number-1));

  }

}