#define bLed 4
#define gLed 5
#define rLed 6
#define yLed 7

#define bBtn 8
#define gBtn 9
#define rBtn 10
#define yBtn 11

int cLed = 0;
int pBtn, check;
unsigned long sTime = 0, fTime = 0;

void setup() {
  for(int i=4 ; i<=7; i++){
    pinMode(i, OUTPUT);
    pinMode(i+4, INPUT_PULLUP);
  }
  Serial.begin(9600);
  randomSeed(analogRead(0));
}

void loop() {
  check = random(4,8);
  while(check == cLed){
    check = random(4,8);
  }
  cLed = check;
  pBtn = cLed + 4;
  digitalWrite(cLed, HIGH);
  sTime = millis();
  while(digitalRead(pBtn) == HIGH){
    delay(10);
  }
  digitalWrite(cLed, LOW);
  fTime = millis();
  delay(200);
  Serial.println(fTime - sTime);
}