HZNUOJ


Problem_ID: B
Result: Accepted
Time: 5ms
Memory: 1116kB
Author: 2018212212077
In contest: 1273

#include<stdio.h>
#include<math.h>
int main(void)
{
	double a,b,c,p;
	while(scanf("%lf%lf%lf",&a,&b,&c)!=EOF)
	{
		p=(a+b+c)/2;
		a+b>c&&a+c>b&&b+c>a?printf("%.2f\n",sqrt(p*(p-a)*(p-b)*(p-c))):printf("invalid triangle\n");
	}
}