[solved]:-How to publish negative values from command line ?

edit

When i try this command.i got an error like this.How can i publish negative values from command line ?

rostopic pub servo std_msgs/UInt16 -180

Usage: rostopic pub /topic type [args...]

rostopic: error: no such option: -8

this is my code:-

#include <ros.h>
#include <std_msgs/Empty.h>
#include <std_msgs/UInt16.h>
signed int angle;
const int stepPin = 9; 
const int dirPin = 8;
int x;

ros::NodeHandle  nh;
void pwm( const std_msgs::UInt16& cmd_msg)
{

angle=cmd_msg.data;
//angle=map(angle,280,1720,-720,720);

 if (angle<0)
 {
 cw();
 delay(100);
 }

 else
 {
 ccw();
 delay(100);
 }


}


ros::Subscriber<std_msgs::UInt16> sub("servo", pwm);

void setup(){
 // pinMode(angle, OUTPUT); 

 pinMode(stepPin,OUTPUT); 
  pinMode(dirPin,OUTPUT);
  nh.initNode();
  nh.subscribe(sub);

 // servo.attach(9); //attach it to pin 9
}

void loop()
{


nh.spinOnce();
  delay(1);
}
void cw()
{
  digitalWrite(dirPin,LOW); 
  for(x = 0; x < 17.77*(angle*-1); x++) {
    digitalWrite(stepPin,HIGH); 
    delayMicroseconds(500); 
    digitalWrite(stepPin,LOW); 
    delayMicroseconds(500); 
  }}
  void ccw()
{
  digitalWrite(dirPin,HIGH); 
  for(x = 0; x < 17.77*angle; x++) {
    digitalWrite(stepPin,HIGH); 
    delayMicroseconds(500); 
    digitalWrite(stepPin,LOW); 
    delayMicroseconds(500); 
  }}