int m = 6;
int h = 4;
int b = 3;
void setup() {
  // put your setup code here, to run once:
pinMode(m, OUTPUT);
pinMode(h, OUTPUT);
pinMode(b, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(m, 255);
digitalWrite(h, 0);
digitalWrite(b, 0);
delay(1000);
digitalWrite(m, 0);
digitalWrite(h, 255);
digitalWrite(b, 0);
delay(1000);
digitalWrite(m, 0);
digitalWrite(h, 0);
digitalWrite(b, 255);
delay(1000);
}