#include <stdio.h>
#include <math.h>
int main()
{
	// 2022.10.21
	float a=0, b=0, c=0;
	float s = 0, area = 0;

	printf("Please input three values of triangle's each lengths\n");
	scanf_s("%f%f%f", &a, &b, &c);

	s = (a + b + c) / 2;
	area = sqrt( s * (s - a) * (s - b) * (s - c));
	printf("The area of the triangle is %f",area);
	return 0;
}