gistfile1.ino

int LED = 13;   // the pin for the LED
int BUTTON = 7; // the input pin where the pushbutton is connected
int val = 0;     // val will be used to store the state of the input pin

int delay_time = 1000;

void setup() {
  pinMode(LED, OUTPUT);   // tell Arduino LED is an output
  pinMode(BUTTON, INPUT); // and BUTTON is an input
}

void loop() {
  while (delay_time > 0) {
    val = digitalRead(BUTTON); // check if the input is HIGH (button pressed)

    delay(delay_time);
    digitalWrite(LED, LOW);
    delay(delay_time);
    
    // if the button is pressed..
    if (val == HIGH) {
      delay_time = delay_time - 1;
    }
  }

  digitalWrite(LED, HIGH);
}