#include <Servo.h>

Servo arm;
float pos = 0.0;
float step = 1.0;

Servo arm2;
float pos2 = 180.0;
float step2 = 1.0;

int state = 1;

void setup()
{
  pinMode(A1, INPUT_PULLUP);

  arm.attach(2);
  arm.write(pos);

  arm2.attach(4);
  arm2.write(pos2);
}

void loop()
{

  if (!digitalRead(A1))
  {
    if (state == 1) {
      while (pos < 180) {
        arm.write(pos);
        arm2.write(pos2);
        pos+=step;
        pos2-=step;
        delay(5);
      }
      state = 2;
    } else {
      while (pos > 0) {
        arm.write(pos);
        arm2.write(pos2);
        pos-=step;
        pos2+=step;
        delay(5);
      }
      state = 1;
    }
  }
}