import "dart:io";

void main() {
  stdout.write("Alap: ");
  String baseStr = stdin.readLineSync() ?? '';
  double base = double.parse(baseStr);
  stdout.write("Magasság: ");
  String heightStr = stdin.readLineSync() ?? '';
  double height = double.parse(heightStr);
  double area = base * height / 2;
  print('Terület: $area');
}