#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)
 setup() {
 Serial.begin(9600);
}

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

}