const unsigned int b1 = 7;
const unsigned int b2 = 6;
const unsigned int b3 = 5;
const unsigned int b4 = 4;


void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(b1,INPUT);
pinMode(b2,INPUT);
pinMode(b3,INPUT);
pinMode(b4,INPUT);
}

void loop() {
int a = digitalRead(b1);
int b = digitalRead(b2);
int c= digitalRead(b3);
int d = digitalRead(b4);
Serial.print(a);
Serial.print(b);
Serial.print(c);
Serial.println(d);
delay(500);
}