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#include "Keypad.h"

char Incoming_value = 0;
String password = "123456";
String input = "";
const byte ROWS = 4; //four rows
const byte COLS = 4; //three columns
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

byte rowPins[ROWS] = {2, 3, 4, 5}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {6,7,8,9}; //connect to the column pinouts of the keypad

Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

void setup()
{
  Serial.begin(9600);
  pinMode(13, OUTPUT);
}

void loop()
{
  if (Serial.available() > 0)
  {
    Incoming_value = Serial.read();
    Serial.print(Incoming_value);
    Serial.print("enter value");
    if (Incoming_value == '1') {
      digitalWrite(13, HIGH);
      Serial.print("ON");
    }
    else if (Incoming_value == '0') {
      Serial.print("OFF");
      digitalWrite(13, LOW);
    }
  }
  // Read the pushed button
  char key = keypad.getKey();
  input = input + key;
  // just print the pressed key
  if (key) {
    Serial.println(key);
  }
  if(key == '*' ){
    Serial.println(input);
    if( input == password){
      digitalWrite(13, HIGH);
    }
  }
  if(key == '#'){
    digitalWrite(13, LOW);
    input = "";
  }
  
/*
  // this checkes if 4 is pressed, then do something. Here  we print the text but you can control something.
  if (key == '4') {
    Serial.println("Key 4 is pressed");
          digitalWrite(13, HIGH);
      Serial.print("ON");
  }
    if (key == '5') {
    Serial.println("Key 5 is pressed");
          digitalWrite(13, LOW);
      Serial.print("ON");
  }
  */
}

when print input variable i get strange text like

⸮⸮⸮⸮⸮⸮⸮;⸮⸮ߵ⸮⸮⸮⸮u⸮⸮⸮⸮⸮⸮?/}⸮⸮⸮⸮⸮⸮~⸮⸮⸮⸮⸮-d

what i can do ?