#include <math.h>

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  float area, p, a, b, c;

  a = 3;
  b = 4;
  c = 5;

  p = (a + b + c) / 2;

  area = sqrt(p * (p - a) * (p - b) * (p - c));
  
  Serial.println(area);

}

void loop() {
  // put your main code here, to run repeatedly:

}