#include<Servo.h>
#define MQSEN A5
Servo myServo1;
Servo myServo2;
Servo myServo3;
Servo myServo4;
void setup(){
    myServo1.attach(9);
    myServo2.attach(11);
    myServo3.attach(3);
    myServo4.attach(6);
    pinMode(MQSEN, INPUT);
    Serial.begin(9600);
}
void loop()
{
 int MQVALUE=analogRead(A5);
if(MQVALUE>500)
{
  myServo1.write(90);
  myServo2.write(90);
   myServo3.write(90);
   myServo4.write(90);
   Serial.println(MQVALUE);
}
else{
  myServo1.write(0);
  myServo2.write(0);
   myServo3.write(0);
   myServo4.write(0);
}
}