#include <Keypad.h>

const byte ROWS = 4; 
const byte COLS = 4; 
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {5, 4, 3, 2}; 
byte colPins[COLS] = {9, 8, 7, 6}; 
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
int x=1;
char key;

void setup() 
{
   Serial.begin(9600);

}

void loop(){
  char key = keypad.waitForKey();
  
  if (key!='3')
  {
    Serial.println(key);
  }
}