三行代码秒了

#include<cstdio>
#include<cmath>
int main(){double a,b,c;scanf("%le%le%le",&a,&b,&c);printf("%.2f",sqrt((a+b+c)/2.0*((a+b+c)/2.0-a)*((a+b+c)/2.0-b)*((a+b+c)/2.0-c)));}