#include <Servo.h>
Servo myservo;
#define buttin 10

void setup() {
  myservo.attach(9);
  myservo.write(0);
  pinMode(buttin, INPUT);
}
int pos=0;
void loop() {
  if(digitalRead(buttin==false) && pos==0){
    pos++;
    delay(10);
    if(pos==180){
      pos--;
      delay(10);
    }
  }
  myservo.write(pos);
  delay(500);
}