interface Figura {
    double pole();
    double obwod();
    double PI = 3.14;
}

class Prostokat implements Figura {
    double arg1;
    double arg2;

    Prostokat(double arg1, double arg2) {
        this.arg1 = arg1;
        this.arg2 = arg2;
    }
    public double pole() {
    return arg1*arg2;
    }
    public double obwod() {
        return arg1+arg1+arg2+arg2;
    }
}

class Trojkat implements Figura {
    double arg1;
    double arg2;
    double arg3;

    Trojkat(double arg1, double arg2, double arg3) {
        this.arg1 = arg1;
        this.arg2 = arg2;
        this.arg3 = arg3;
    }
    public double pole() {
    return sqrt(((arg1+arg2+arg3)*(arg1+arg2-arg3)*(arg1-arg2+arg3)*(-arg1+arg2+arg3))/4);
    }

    public double obwod() {
        return arg1+arg2+arg3;
    }
}

class Kolo implements Figura {
    double arg1;
    double PI;

    Kolo(double arg1, double PI) {
        this.arg1 = arg1;
        this.PI = PI;
    }
    public double pole() {
        return PI*(arg1*arg1);
    }
    public double obwod() {
        return 2*PI*arg1;
    }
}