小题解（函数

#include<bits/stdc++.h>
using namespace std;
int check(double a,double b,double c){
    double p,q;
    p=(a+b+c)/2.0;
    q=sqrt(p*(p-a)*(p-b)*(p-c));
    cout<<setprecision(2)<<fixed<<q<<endl;
}
int main(){
	double n1,n2,n3;
	cin>>n1>>n2>>n3;
        check(n1,n2,n3);
	return 0; 
}