#pragma GCC push_options
#pragma GCC optimize ("Os")
#include <core.h> // Required by cpu
#include <cpu.h>
#pragma GCC pop_options
// Peripheral Constructors
CPU &cpu = Cpu;



const int rin = 2;
const int led = 13;    

//void prerus();

void setup() 
{
//  Serial.begin(9600);
//  Serial.print("setup");
//  Serial.println();
  pinMode(rin, INPUT_PULLUP);
  pinMode(13, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(2), prerus, RISING);
}

void loop() 
{
//Serial.print("loop");
//digitalWrite(13, LOW);
//Serial.println();
//delay(100);
}


void prerus() 
{
digitalWrite(13, HIGH);
delay(4);
digitalWrite(13,LOW);
//  Serial.print("interrupt");
//  Serial.println();
}