Social Distancing Reminders

const int trigPin = 4;
const int echoPin = 3;
long duration;
int distance;
int a=0;

void setup() 
 {
  pinMode(trigPin, OUTPUT);
  pinMode(5, OUTPUT); 
  pinMode(echoPin, INPUT); 
  Serial.begin(9600);
  }
void loop() {
    digitalWrite(trigPin, LOW);delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    duration = pulseIn(echoPin, HIGH);
    distance= duration/58.2;
    Serial.println(distance);
    delay(100);
         if(distance<=100){digitalWrite(5, HIGH);}
    else if(distance> 100){digitalWrite(5, LOW);}
    }