int red = 9;
int green = 3;
int blue = 5;

int but = 4;
int count =0;
int st,old_st;

void setup() {
pinMode(red, OUTPUT);
pinMode(green, OUTPUT);
pinMode(blue, OUTPUT);
 pinMode(but, INPUT_PULLUP);
 Serial.begin(9600);
}

void loop() {
readBut();  

if (count == 1 ){
  digitalWrite(red, HIGH);
  digitalWrite(green, LOW);
  digitalWrite(blue, LOW);
}
else if (count == 2){
  digitalWrite(green, HIGH);
  digitalWrite(red, LOW);
  digitalWrite(blue, LOW);
}
else if (count == 3){
  digitalWrite(blue, HIGH);
  digitalWrite(red, LOW);
  digitalWrite(green, LOW);
}
else if (count == 0){
  digitalWrite(green, LOW);
  digitalWrite(red, LOW);
  digitalWrite(blue, LOW);
}
}

void readBut(){
st = !digitalRead(but);
if (st==1 && old_st ==0){
count++;
}
else{
  delay(50);
}
if (count == 4){
  count = 0;
}
old_st = st;
Serial.println(count);

}