#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]={9,8,7,6};
byte colPins[COLS]={5,4,3,2};
Keypad customKeypad = Keypad(makeKeymap(keys),rowPins,colPins,ROWS,COLS);
void setup() 
{
 Serial.begin(9600);
}

void loop()
{
  char customKey = customKeypad.getKey();
  if(customKey)
  {
    Serial.println(customKey);
  }
}