#include <stdio.h>
#include <math.h>
#include <inttypes.h>
#include <stdint.h>
#include <random>

double f1
(
  double x1, double y1, double z1,
  double x2, double y2, double z2,
  double x3, double y3, double z3
)
{
  double a = fabsl((x2-x1)*(y3-y1)-(x3-x1)*(y2-y1))/2.0;
  a = a*a*a;
  return a;
}


int main()
{
  std::random_device rd;
  std::mt19937 gen(rd());
  std::uniform_real_distribution<> dis(0, 1);
  double random_number = dis(gen);

  double acc = 0;
  #define END INTMAX_C(500000000)
  for (size_t i = 0; i < END; i++)
  {
    acc += f1(dis(gen),dis(gen),dis(gen),dis(gen),dis(gen),dis(gen),dis(gen),dis(gen),dis(gen));
  }
  printf("%f\n", (acc/1)/END);
  return (0);
}