Counter Up Arduino Bluetooth

Wiring
Arduino With IR Obstacle
PIN 7 --------------- Out
5V ---------------- 5V
GND --------------- GND

Arduino With Bluetooth HC05
        Tx ---------------- Rx
Rx ---------------- Tx
5V ---------------- 5V
GND --------------- GND

Arduino Sketch
int n;
void setup () {
  pinMode (7, INPUT);
  Serial.begin (9600);
}
void loop () {
    
    if (digitalRead (7) == LOW) {
        n ++;
        Serial.print (n);
             delay (1000);
                 }
}