Simple Code to take input from user

#include <Keypad.h>
long value = 0;
const byte ROWS = 4; //four rows
const byte COLS = 4; //four columns
char keys[ROWS][COLS] = {
  {'1', '4', '7', '*'},
  {'2', '5', '8', '0'},
  {'3', '6', '9', '#'},
  {'A', 'B', 'C', 'D'}
};
byte rowPins[ROWS] = {7, 6, 5, 4}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {11, 10, 9, 8}; //connect to the column pinouts of the keypad
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
void setup() {
  Serial.begin(9600);
}
void loop() {

  char key = keypad.getKey();
  if (key == 'A' || key == 'B' || key == 'C' || key == 'D') {
    Serial.print("");
  }
  else Serial.print(key);
  delay(1);
  if (key != NO_KEY)
  {
    if ( (key >= '0') && (key <= '9') )
    {
      value = value * 10;
      value = value + key - '0';
    }
    if ( key == 'A' )
    {
      Serial.println();
      Serial.println(value);
      // Remove this line and add it to the sensor value checker complete
      value = 0; //Now reset ready for next input
    }
  }
  if (key == 'B')
  {
    value = 0; //Now reset ready for next input
    Serial.println();
    Serial.println("Enter A New Number Please:");
  }
  if (key == 'C')
  {
    // Do whatever you like
    //digitalWrite(ValvePin, LOW); // if relay is Active LOW
  }
  if (key == 'D')
  {
    // Do whatever you like
    //digitalWrite(ValvePin, HIGH); // if relay is Active LOW
  }

}//end of loop