#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() 
{ 
  while(digitalRead(S0)==LOW);

  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);
}