Edge Avoiding Robot Using IR sensor

#define MLa 8
#define MLb 9
#define MRa 10
#define MRb 11
#define Sensor 2
void setup()
{
pinMode(Sensor, INPUT);
pinMode(MLa, OUTPUT);
pinMode(MLb, OUTPUT);
pinMode(MRa, OUTPUT);
pinMode(MRb, OUTPUT);
Serial.begin(9600);
}
void loop()
{
int Sensorin=digitalRead(Sensor);
Serial.println(Sensorin);
delay(100);
if(Sensorin==LOW)
{//forward
digitalWrite(MLa,HIGH);
digitalWrite(MLb,LOW);
digitalWrite(MRa,HIGH);
digitalWrite(MRb,LOW);
}
else{//Stop
digitalWrite(MLa,LOW);
digitalWrite(MLa,LOW);
digitalWrite(MLa,LOW);
digitalWrite(MLa,LOW);
delay(300);
//backward
digitalWrite(MLa,LOW);
digitalWrite(MLa,HIGH);
digitalWrite(MLa,LOW);
digitalWrite(MLa,HIGH);
delay(500);
//Stop
digitalWrite(MLa,LOW);
digitalWrite(MLa,LOW);
digitalWrite(MLa,LOW);
digitalWrite(MLa,LOW);
delay(300);
//Rightturn
digitalWrite(MLa,HIGH);
digitalWrite(MLa,LOW);
digitalWrite(MLa,LOW);
digitalWrite(MLa,LOW);
delay(500);
}
}