Marker Beacon System with IR Sensors, Buzzer and LED

int irInner=6,irMiddle=7,irOuter=8,irRunway=10;
int ledInner=4,ledMiddle=2,ledOuter=3;
int sound = 11;              // Declaration of variables with pin numbers of components
int valIn=0,valMd=0,valOt=0,valRunway=0;
int check1=0, check2=0, check3=0;  // Declaration and initialization of variables

void setup()
{
  
  Serial.begin(9600);
  
  pinMode(irInner, INPUT_PULLUP);  // input component
  pinMode(ledInner, OUTPUT);       //output component
  
   pinMode(irMiddle, INPUT_PULLUP);
  pinMode(ledMiddle, OUTPUT);
  
   pinMode(irOuter, INPUT_PULLUP);
  pinMode(ledOuter, OUTPUT);

  pinMode(irRunway,INPUT_PULLUP); 
  
}

void loop()
{
 
  valIn=digitalRead(irInner);  //getting current state of sensor(HIGH or LOW)
  valMd=digitalRead(irMiddle);
  valOt=digitalRead(irOuter);
  valRunway=digitalRead(irRunway);


      if(valOt==LOW  )  //if obstacle on outer sensor
      {
        digitalWrite(ledOuter, HIGH); //led on
        check1=1;
      }
      else
      {
        digitalWrite(ledOuter,LOW); //led off
      }

  
      if(valMd==LOW )
      { 
        digitalWrite(ledMiddle, HIGH);
        check1=0;
        check2=1;
      }
      else
      {
        digitalWrite(ledMiddle, LOW);
      }
     
      
      if(valIn==LOW  )
      {  
        digitalWrite(ledInner, HIGH);
        check3=1;
        check2=0;
      } 
      else
      {
        digitalWrite(ledInner, LOW);
      }

       if(valRunway==LOW)
       {
       check3=0;
        delay(6000);  //programme execution delay for 6 sec
       }

  
      if(check1==1) //
      {
        tone(sound, 1000, 350); //buzzer or speaker making sound
        delay(500);
      }
      if(check2==1)
      {
        tone(sounds, 4000, 100);
        delay(150);
        tone(sounds, 1000, 150);
        delay(300);

      }
      if(check3==1)
      {
          tone(sound, 4000, 100);
        delay(150);
      }
      
}