public class Server {

private double a;
private double b;
private String c;

public Server() {
    a = 0;
    b = 0;
    c = "";
}

public void getVar(double x, String temp){
    a = x;
    c += temp;
}
public void getVar(double x, double y, String temp){
    a = x;
    b = y;
    c += temp;
}

public double Add(double x, double y){
    return x + y;
}

public double Subtract(double x, double y){
    return x - y;
}

public double Multiply(double x, double y){
    return x * y;
}

public double Divide(double x, double y){
    return x / y;
}
public double Sqrt(double x){
    return Math.sqrt(x);
}

public double Abs(double x){
    return Math.abs(x);
}

public double Pow(double x, double y){
    return Math.pow(x, y);
}

public String toString(){
    double f = 0;
    if(c.equals("a"))
       f = Add(a, b);
    else if(c.equals("s"))
       f = Subtract(a, b);
    else if(c.equals("m"))
       f = Multiply(a, b);
    else if(c.equals("d"))
       f = Divide(a, b);
    else if(c.equals("sq"))
        f = Sqrt(a);
    else if(c.equals("abs"))
        f = Abs(a);
    else if(c.equals("pow"))
        f = Pow(a, b);
    return "Your answer is: " + f;
}
}