int rled = 10, gled = 11, bled = 12;
int last = LOW;
int current = LOW;
int ledon = 10;
int BUTTON = 2;

void setup() {
  // put your setup code here, to run once:
  pinMode(rled, OUTPUT);
  pinMode(gled, OUTPUT);
  pinMode(bled, OUTPUT);
  pinMode(2, INPUT);
  digitalWrite(ledon, HIGH);
}

boolean debounce(boolean last)
{
  boolean current = digitalRead(BUTTON);       // Read the button state
  if (last != current)                         // If it's different…
  {
    delay(5);                                  // Wait 5ms
    current = digitalRead(BUTTON);             // Read it again
  }
  return current;                              // Return the current value
}

void loop() {
  
  current = debounce(last);              // Read debounced state
  if (last == LOW && current == HIGH)    // If it was pressed…
  {
    digitalWrite(ledon, LOW);
    ledon += 1;
    if (ledon > 12) ledon = 10;
  }
  last = current;                        
  digitalWrite(ledon, HIGH);
}