#define RED 6
#define GREEN 5
#define BLUE 3

#define buttonRpin 12
#define buttonGpin 10
#define buttonBpin 8

#define stepSize 1
#define delayTime 5

void setup() {
  pinMode(RED, OUTPUT);
  pinMode(BLUE, OUTPUT);
  pinMode(GREEN, OUTPUT);
  pinMode(buttonRpin, INPUT_PULLUP);
  pinMode(buttonBpin, INPUT_PULLUP);
  pinMode(buttonGpin, INPUT_PULLUP);
  digitalWrite(RED, LOW);
  digitalWrite(BLUE, LOW);
  digitalWrite(GREEN, LOW);
}

int redValue = 0;
int blueValue = 0;
int greenValue = 0;

void loop() {
  if (digitalRead(buttonRpin) == LOW) {
    redValue += stepSize;
    if (redValue == 255) {
      redValue = 0;
    }
    analogWrite(RED, redValue);
    delay(delayTime);
  }
  if (digitalRead(buttonBpin) == LOW) {
    blueValue += stepSize;
       if (blueValue == 255) {
        blueValue = 0;
      }
    analogWrite(BLUE, blueValue);
    delay(delayTime);
  }
  if (digitalRead(buttonGpin) == LOW) {
    greenValue += stepSize;
       if (greenValue == 255) {
        greenValue = 0;
      }
    analogWrite(GREEN, greenValue);
    delay(delayTime);
  }
}