#define ledRed 13
#define ledYellow 12
#define ledGreen 11
#define ledBlue 10
#define key 7
int led[]={ledRed, ledYellow, ledGreen, ledBlue};

void setup() {
  for (int i=0; i<4; i++) {
    pinMode(led[i], OUTPUT);
    pinMode(key, INPUT);
    //digitalWrite(led, LOW);
  }
}
int i=0;

void loop() {
  if (digitalRead(key)) {
    i++;
    if (i==4) {
      i=0;
    }
  }
  else {
    i--;
    if (i== -1) {
      i=3;
    }
  }
  digitalWrite(led[i], 1);
  delay(300);
  digitalWrite(led[i], 0);
    
}