void setup()
{
    pinMode (13 , OUTPUT);
    pinMode (11 , OUTPUT);
    pinMode (10 , OUTPUT);
}

void loop()
{
    digitalWrite (13 , HIGH);
    digitalWrite (11 , HIGH);
    digitalWrite (10 , HIGH);
    delay ( 1000);  
    
    digitalWrite (13 , LOW);
    digitalWrite (11 , LOW);
    digitalWrite (10 , LOW);
    delay ( 1000);
}