#include <Servo.h>
#define echoPin 2
#define trigPin 3
long duration;
int distance;
Servo S;
int position;

void setup()
{
  pinMode(trigPin,OUTPUT);
  pinMode(echoPin,INPUT);
  S.attach(7);
}

void loop()
{
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;

  if (distance <50) {
  for(position=0; position<=100; position++){
    S.write(position);
    delay(100);
  }
  delay(10000);
  }
  else if (distance>50){
    for(position=100; position>=0; position--){
  S.write(position);
  delay(15);
  delay(500);
  }
delay(10000);
}
}