#include <Keypad.h>
const uint8_t ROWS = 4;
const uint8_t COLS =4;
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4','5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#','D'}
};
uint8_t colPins[COLS] = {5, 4, 3,2};
uint8_t rowPins[ROWS] = {9,8,7,6};
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
char key = keypad.getKey();
if (key !=NO_KEY)
{
  Serial.println(key);
}
}