int led1=0;
int led2=1;
int led3=2;
int led4=3;
int led5=4;
void setup() {
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
pinMode(led3, OUTPUT);
pinMode(led4, OUTPUT);
pinMode(led5, OUTPUT);

}

void loop() {
 digitalWrite(led1, HIGH);
 
 delay(50);
 digitalWrite(led1, LOW);
 delay(50);
 
 digitalWrite(led2, HIGH);
 
 delay(50);
 digitalWrite(led2, LOW);
 digitalWrite(led3, HIGH);
 delay(50);
 digitalWrite(led3, LOW);
 digitalWrite(led4, HIGH);
 delay(50);
 digitalWrite(led4, LOW);
 digitalWrite(led5, HIGH);
 delay(50);
 digitalWrite(led5, LOW);
 delay(50); 
  
}