void setup() 
{
pinMode(12, OUTPUT);
pinMode(8, OUTPUT);
pinMode(7, OUTPUT);
}
int muster = 0;
void loop() 
{
 
    if(muster <=10)
        {
        digitalWrite(12, LOW);
        digitalWrite(8, LOW);
        digitalWrite(7, HIGH);
        }
  else if(muster <=20)
        {
        digitalWrite(12, LOW);
        digitalWrite(8, HIGH);
        digitalWrite(7, LOW);
        }
  else if(muster <=30)
        {
        digitalWrite(12, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(7, LOW);
        }
  muster = muster +1;
  if (muster >30)
{
  muster = 0;
}
 delay (50);




    if(muster <=10)
        {
        digitalWrite(12, LOW);
        digitalWrite(8, HIGH);
        digitalWrite(7, HIGH);
        }
  else if(muster <=20)
        {
        digitalWrite(12, LOW);
        digitalWrite(8, HIGH);
        digitalWrite(7, LOW);
        }
  else if(muster <=30)
        {
        digitalWrite(12, HIGH);
        digitalWrite(8, HIGH);
        digitalWrite(7, LOW);
        }
  muster = muster +1;
  if (muster >30)
{
  muster = 0;
}
 delay (50);




    if(muster <=10)
        {
        digitalWrite(12, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(7, LOW);
        }
  else if(muster <=20)
        {
        digitalWrite(12, LOW);
        digitalWrite(8, HIGH);
        digitalWrite(7, LOW);
        }
  else if(muster <=30)
        {
        digitalWrite(12, LOW);
        digitalWrite(8, LOW);
        digitalWrite(7, HIGH);
        }
  muster = muster +1;
  if (muster >30)
{
  muster = 0;
}
 delay (50);

}