#include <Keypad.h>
const byte rows=4;
const byte cols=4;
char hexakeys[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(hexakeys),rowpins,colpins,rows,cols);

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

}

void loop() {
  char customkeys=customKeypad.getKeys();
  if (customkeys){
    Serial.println(customkeys);
  }
  // put your main code here, to run repeatedly:

}