using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace Main
{
class Program
static void Main(string[] args)
double b,h;
Console.WriteLine("Ingresa base");
b = Convert.ToDouble(Console.ReadLine());
Console.WriteLine("Ingresa altura");
h = Convert.ToDouble(Console.ReadLine());
double area;
area=b*h/2;
Console.WriteLine(area);
Console.ReadLine();
}