Radar using buzzer

#include<Servo.h>

int trig =10;
int echo=9;
int buzzer=2;

Servo myservo;

void setup() 
{
  // put your setup code here, to run once:
pinMode(trig,OUTPUT);
pinMode(echo,INPUT);
pinMode(buzzer,OUTPUT);
myservo.attach(11);
Serial.begin(9600);

}

void loop() 
{
  // put your main code here, to run repeatedly:
for(int i=0;i<180;i++)
{
  myservo.write(i);
  delay(30);
  if (calc_dis()<=50 && calc_dis()>=5)
  {
    Serial.print("distance-");
    Serial.print(calc_dis());
    digitalWrite(buzzer,HIGH);
    delay(1000);
    Serial.print(">>");
    Serial.print(buzzer);
  }
  
}
for(int i=180;i>0;i--)
{
  myservo.write(i);
  delay(30);
  if (calc_dis()<=50 && calc_dis()>=5)
  {
    Serial.print("distance-");
    Serial.print(calc_dis());
    digitalWrite(buzzer,HIGH);
    delay(1000);
    Serial.print(">>");
    Serial.print(buzzer);
  }
  
}
delay(60);
}
int calc_dis()
{
  int distance;
  int duration;
  digitalWrite(trig,HIGH);
  delay(1);
  digitalWrite(trig,LOW);
  
  duration=pulseIn(echo,HIGH);
  
  distance=(duration/2)/29.1;
  return distance;
}