import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System. in);
double x1 = input.nextDouble();
double y1 = input.nextDouble();
double x2 = input.nextDouble();
double y2 = input.nextDouble();
double x3 = input.nextDouble();
double y3 = input.nextDouble();
double s1 = Math.sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
double s2 = Math.sqrt((x3-x2)*(x3-x2) + (y3-y2)*(y3-y2));
double s3 = Math.sqrt((x1-x3)*(x1-x3) + (y1-y3)*(y1-y3));
double s = (s1 + s2 + s3)/2;
double area = Math.sqrt(s*(s-s1)*(s-s2)*(s-s3));
System.out.printf("%.1f\n",area);
}
}
예시 문제에 대한 결과값은 나오는데 wrong answer가 뜹니다..!
