int led1= 2;
int led2= 4;
int led3= 16;
int led4= 17;
int led5= 5;
int led6= 18;
int led7= 19;
int led8= 21;
void setup() {
 pinMode(2,OUTPUT);
 pinMode(4,OUTPUT);
 pinMode(16,OUTPUT);
 pinMode(17,OUTPUT);
pinMode(5,OUTPUT);
pinMode(18,OUTPUT);
pinMode(19,OUTPUT);
pinMode(21,OUTPUT);
}

void loop() {
 digitalWrite(led1,1);
 delay(500);
 digitalWrite(led2,1);
 delay(500);
 digitalWrite(led3,1);
 delay(500);
 digitalWrite(led4,1);
 delay(500);
 digitalWrite(led5,1);
 delay(500);
 digitalWrite(led6,1);
 delay(500);
 digitalWrite(led7,1);
 delay(500);
 digitalWrite(led8,1);
 delay(500);
 digitalWrite(led1,0);
 digitalWrite(led2,0);
 digitalWrite(led3,0);
 digitalWrite(led4,0);
 digitalWrite(led5,0);
 digitalWrite(led6,0);
 digitalWrite(led7,0);
 digitalWrite(led8,0);
 delay(500);
 digitalWrite(led8,1);
 digitalWrite(led7,1);
 digitalWrite(led6,1);
 digitalWrite(led5,1);
 digitalWrite(led4,1);
 digitalWrite(led3,1);
 digitalWrite(led2,1);
 digitalWrite(led1,1);
delay(500);
 digitalWrite(led8,0);
 delay(500);
digitalWrite(led7,0);
delay(500);
 digitalWrite(led6,0);
 delay(500);
 digitalWrite(led5,0);
 delay(500);
 digitalWrite(led4,0);
 delay(500);
 digitalWrite(led3,0);
 delay(500);
 digitalWrite(led2,0);
 delay(500);
 digitalWrite(led1,0);
delay(500);
}