public class Triangle {

    public static void main(String[] args) {
        Sides sides = new Sides(30, 35, 40);
        double perimeter = calcPerimeter(sides);
        System.out.println("Perimeter: " + perimeter);
    }

    public static double calcPerimeter(Sides sides) {        
        double perimeter = -1;
        if(isEditable(sides)) {
            perimeter = sides.a + sides.b + sides.c;
        }
        return perimeter;
    }
    
    public static boolean isEditable(Sides sides) {
        boolean editable = true;
        if(sides.a + sides.b < sides.c) {
            editable = false;
        }
        if(sides.a + sides.c < sides.b) {
            editable = false;
        }
        if(sides.b + sides.c < sides.a) {
            editable = false;
        }
        return editable;
    }
}