#include<iostream>
#include<cmath>
#include<ctime>
#include<cstdlib>

using namespace std;

void compute_area(double&,double&,double,double,double);

int main()
{
    double area,perimeter;
    double a,b,c;

 
    cout<<"Enter length a: ";
    cin>>a;
    cout<<endl;

    cout<<"Enter length b: ";
    cin>>b;
    cout<<endl;

    cout<<"Enter length c: ";
    cin>>c;
    cout<<endl;
    
    compute_area(area,perimeter,a,b,c);
    
  return 0;
}//end main


void compute_area (double& area, double& perimeter, double a, double b,
double c)
{   
    double s;
    //s=0;

    if( (a>(b+c))||(b>(a+c))||(c>(b+a)) )
     {   cout<<"bad combination!"<<endl;
         return;
      }

    else
     {
         s = (a + b + c)/ 2.0;
         area = sqrt (s*(s-a)*(s-b)*(s-c));
         perimeter=a+b+c;
         cout << "The area of a triangle with sides of length " << a
         << ", " << b << " and " << c << " is " << area <<
         " and its perimeter is "<<perimeter<< endl;
         return;
     }   
}