#include <Servo.h>
int ser_pin = 11;
int pos = 0;
Servo servo1;
void setup()
{
 pinMode(12, INPUT);
 servo1.attach(ser_pin);
}
void loop() {
 int motion = digitalRead(12);
 if ( motion == HIGH) { // Line A

 for (pos = 0;pos <= 180; pos+=1 ) {// Line B
 servo1.write(pos);
 delay(30);
 }
 delay(3000);

 for (pos = 180; pos>=0; pos-=1  ) { // Line C
 servo1.write(pos);
 delay(30);
 }
 delay(30);
 }
}