int ledPin1 = 10;
int ledPin2 = 11;
int ledPin3 = 12;
int ledPin4 = 13;
int inPin = 7;  // pushbutton connected to digital pin 2
int val = 0;    // variable to store the read value

int index = -1;  // to indicate which led should be turned on

// the setup function runs once when you press reset or power the board
void setup() {
  pinMode(ledPin1, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  pinMode(ledPin3, OUTPUT);
  pinMode(ledPin4, OUTPUT);
  pinMode(inPin, INPUT);
}  // the loop function runs over and over again forever
void loop() {

  val = digitalRead(inPin);

  if (val == 1) {  // the button is pushed
    // turn off the LED which is on now
    if (index != -1) {  // if index is not the initial value
      switch (index) {
        case 0:
          digitalWrite(ledPin1, LOW);  // turn the LED off (LOW is the voltage level)
          delay(50);
          break;
        case 1:
          digitalWrite(ledPin2, LOW);
          delay(50);
          break;
        case 2:
          digitalWrite(ledPin3, LOW);
          delay(50);
          break;
        case 3:
          digitalWrite(ledPin4, LOW);
          delay(50);
          break;
      }
    }

    // turn on the next LED
    index++;
    index = index % 5;
    switch (index) {
      case 0:
        digitalWrite(ledPin1, HIGH);  // turn the LED on (HIGH is the voltage level)
        delay(250);
        break;
      case 1:
        digitalWrite(ledPin2, HIGH);
        delay(250);
        break;
      case 2:
        digitalWrite(ledPin3, HIGH);
        delay(250);
        break;
      case 3:
        digitalWrite(ledPin4, HIGH);
        delay(250);
        break;
      case 4:
        digitalWrite(ledPin1, LOW);
        digitalWrite(ledPin2, LOW);
        digitalWrite(ledPin3, LOW);
        digitalWrite(ledPin4, LOW);
        delay(250);
        break;
    }
  }
}