// Code by Shimon Tolts
// OpenUni Java Course
import java.util.Scanner;
public class Triangle {
    public static void main(String[] args) {
        Scanner scan = new Scanner (System.in);
        System.out.println ("Please enter 3 integers Triangle");
        //receiving input from the user
        int a = scan.nextInt();
        int b = scan.nextInt();
        int c = scan.nextInt();
        //performing a check if the input is valid
        if ((a >= b+c || b >= a+c || c >= a+b)) {
            System.out.print("Your input: " +a+" "+b+" "+c+" is invalid");
        } else {
            double s = (a + b +c) / 2.0;
            double d = Math.sqrt(((s-a)*(s-b)*(s-c)*s));
            //printing the result of the area of a triangle
            System.out.print("The area of a triangle is: "+ d);
        }
    }
}