int sen1=11;

int sen2=12;

int sen13=13;

void setup() {

// initialize the digital pin as an output.

// Pin 13 has an LED connected on most Arduino boards:

pinMode(11, OUTPUT);

pinMode(12, OUTPUT);

pinMode(13, OUTPUT);

}

void loop() {

digitalWrite(11, HIGH);

digitalWrite(12, LOW);

digitalWrite(13, LOW);

delay(1000);

digitalWrite(12, HIGH);

digitalWrite(13, LOW);

digitalWrite(11,LOW);

delay(1000);

digitalWrite(11, LOW);

digitalWrite(12, LOW);

digitalWrite(13, HIGH);

delay(1000);

digitalWrite(11, HIGH);

digitalWrite(12, HIGH);

digitalWrite(13, HIGH);

delay(1000);

digitalWrite(11, LOW);

digitalWrite(12, LOW);

digitalWrite(13, LOW);

delay(1000);

}