#define LED 7  // define the led pin
#define BTN 3  // define the button pin

// Variables will change:
bool previous_state = 0;    // previous state of the button
int i = 1;  // index delay

// the values of delay
int delays[3] = {100, 200, 500};

void setup() {

  // set the led pin like output
  pinMode(LED, OUTPUT);

  // set the button pin like input
  pinMode(BTN, INPUT_PULLUP);
}

void loop() {
  // read the pushbutton input pin:
  bool button_state = digitalRead(BTN);

  // compare the buttonState to its previous state
  if (button_state != previous_state) {
    // if button has pressed, increment the counter
    if (!button_state) {
      i++;
      if (i > 2) i = 0;
    }
  }
  // save the current state as the last state,
  //for next time through the loop
  previous_state = button_state;

  //blink
  digitalWrite(LED, HIGH);
  delay(delays[i]);
  digitalWrite(LED, LOW);
  delay(delays[i]);

}