>>801
import java.util.Random;
public class Monte {
  public static void main(String[] args) {
    Random rand = new Random();
    int maxCount = 10000;
    int inCount = 0;
    for (int i = 0; i < maxCount; i++) {
      double x = rand.nextDouble();
      double y = rand.nextDouble();
      if (y <= Math.sin(x * Math.PI / 2)) {
        inCount++;
      }
    }
    System.out.println(Math.PI / 2 * inCount / maxCount);
  }
}