#include<iostream>
#include<math.h>
using namespace std;

// 三角形类的定义
class Tri {
private:
    double side1, side2, side3; 

public:
    Tri(double s1, double s2, double s3) {
        side1 = s1;
        side2 = s2;
        side3 = s3;
    }

    double perimeter() {
        return side1 + side2 + side3;
    }

    double area() {
        double s = (side1 + side2 + side3) / 2;
        return sqrt(s * (s - side1) * (s - side2) * (s - side3));
    }

    void print() {
        if (side1 + side2 > side3 && side1 + side3 > side2 && side2 + side3 > side1) {
        	cout << "三角形的边长:" << side1 << " " << side2 << " " << side3 << endl;
            cout << "三角形的周长:" << perimeter() << endl;
            cout << "三角形的面积:" << area() << endl;
        } else {
            cout << "不构成三角形!" << endl;
        }
    }
};

int main() {
    double s1, s2, s3;
    cin >> s1 >> s2 >> s3;

    Tri triangle(s1, s2, s3);
    triangle.print();

    return 0;
}