Expected unqualified-id before “if” Hatası ve Örnek Kod

int trigPin=7;
int echoPin=8;

int motorA1 = 5; 
int motorA2 = 6; 
int motorB1 = 9; 
int motorB2 = 10; 

int onsagled = 13;
int onsolled = 12;
int arkasagled = 3;
int arkasolled = 4;
int gazalarmiicinicerdekiled=11;

int buzzer = 7;

int vel = 255; 
int state = '0';

void setup() { 
Serial.begin(9600); 
pinMode(motorA1, OUTPUT);
pinMode(motorA2, OUTPUT);
pinMode(motorB1, OUTPUT);
pinMode(motorB2, OUTPUT);
pinMode(onsagled,OUTPUT);
pinMode(onsolled,OUTPUT);
pinMode(arkasagled,OUTPUT);
pinMode(arkasolled,OUTPUT);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
} 

void loop() { 
  
int sure, mesafe;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  sure = pulseIn(echoPin, HIGH);
  mesafe = (sure/2) / 29.1;

int isik = analogRead(A5);  
Serial.println(isik);
delay(500);

if(Serial.available()>0){ 
state = Serial.read();
}

if (state == '0'){
      vel=0;}
    else if (state == '1'){
      vel=100;}
    else if (state == '2'){
      vel=180;}
    else if (state == '3'){
      vel=200;}
    else if (state == '4'){
      vel=255;}