node mcu code with mqtt server io.adafruit

#include <ESP8266WiFi.h>
#include "Adafruit_MQTT.h"
#include "Adafruit_MQTT_Client.h"
// WiFi parameters
#define WLAN_SSID       "Network"
#define WLAN_PASS       "123456789"

// Adafruit IO
#define AIO_SERVER      "io.adafruit.com"
#define AIO_SERVERPORT  1883
#define AIO_USERNAME    "project961"
#define AIO_KEY         "aio_Otov68k9Tf4vrfClHHM7keoEiuDQ"  // Obtained from account info on io.adafruit.com

// Create an ESP8266 WiFiClient class to connect to the MQTT server.
WiFiClient client;

// Setup the MQTT client class by passing in the WiFi client and MQTT server and login details.
Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_KEY);

Adafruit_MQTT_Publish Attendance = Adafruit_MQTT_Publish(&mqtt, AIO_USERNAME "/feeds/COUNT");

char ID;
/*************************** Sketch Code ************************************/

void setup() {
  Serial.begin(115200);
  Serial.println(F("Adafruit IO Example"));

  // Connect to WiFi access point.
  Serial.println(); Serial.println();
  delay(10);
  Serial.print(F("Connecting to "));
  Serial.println(WLAN_SSID);

  WiFi.begin(WLAN_SSID, WLAN_PASS);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(F("."));
  }
  Serial.println();

  Serial.println(F("WiFi connected"));
  Serial.println(F("IP address: "));
  Serial.println(WiFi.localIP());

  // connect to adafruit io
  connect();

}

// connect to adafruit io via MQTT
void connect() {
  Serial.print(F("Connecting to Adafruit IO... "));
  int8_t ret;
  while ((ret = mqtt.connect()) != 0) {
    switch (ret) {
      case 1: Serial.println(F("Wrong protocol")); break;
      case 2: Serial.println(F("ID rejected")); break;
      case 3: Serial.println(F("Server unavail")); break;
      case 4: Serial.println(F("Bad user/pass")); break;
      case 5: Serial.println(F("Not authed")); break;
      case 6: Serial.println(F("Failed to subscribe")); break;
      default: Serial.println(F("Connection failed")); break;
    }

    if (ret >= 0)
      mqtt.disconnect();

    Serial.println(F("Retrying connection..."));
    delay(5000);
  }
  Serial.println(F("Adafruit IO Connected!"));
}

void loop() {
  // ping adafruit io a few times to make sure we remain connected
  if (! mqtt.ping(3)) {
    // reconnect to adafruit io
    if (! mqtt.connected())
      connect();
  }
  if ( Serial.available() ) { // Update and send only after 1 seconds
    char a = Serial.read();
    ID = a;

    if (! Attendance.publish(ID)) {                     //Publish to Adafruit
      Serial.println(F("Failed"));
    } else {
      Serial.println(F("Sent!"));
    }

  }
  //delay(2000);
}