#define S0 2
#define B1 3
#define B2 4
#define B3 5
#define B4 6
#define Y1 A0
#define Y2 A1
#define Y3 A2
#define H A3
#define RW A4

void setup() { 
  pinMode(S0, INPUT_PULLUP); 
  pinMode(B1, INPUT_PULLUP);  
  pinMode(B2, INPUT_PULLUP);
  pinMode(B3, INPUT_PULLUP);
  pinMode(B4, INPUT_PULLUP);
  pinMode(Y1, OUTPUT);
  pinMode(Y2, OUTPUT);
  pinMode(Y3, OUTPUT);
  pinMode(H, OUTPUT);
  pinMode(RW, OUTPUT);
}

void loop() {   
  if(digitalRead(S0) == HIGH){
    digitalWrite(Y1, HIGH); 
     digitalWrite(Y3, LOW);
     while(digitalRead(B2) == LOW);
     digitalWrite(Y1, LOW);
     digitalWrite(Y2, HIGH);
     digitalWrite(RW, HIGH);
      while(digitalRead(B3) == LOW);
       digitalWrite(Y2, LOW);
       digitalWrite(RW, LOW);
       digitalWrite(H, HIGH);
       while(digitalRead(B4) == LOW);
       digitalWrite(Y3, HIGH);
       digitalWrite(H, LOW);
      while(digitalRead(B1) == LOW);
  };
}