void setup() {
  // put your setup code here, to run once:
pinMode (2, OUTPUT);
}
int zalupa (int a,int i) {
  int z=a+i;
  return z;
}
int zalupa1 (int a,int i) {
  int z=a-i;
  return z;
}

void loop() {
  // put your main code here, to run repeatedly:
  int l=20;
  int u=15;
int x=zalupa(l, u);
int p=zalupa1(l, u);

if (p!=6){
  const int D=300;
  int a=D;
  a=a+1;
  a++;
  a+= 1;
  for (int i=5; i>-5; i=i-2){
  digitalWrite (2, 1);
  delay (D);
  digitalWrite (2, 0);
  delay (D);
  }
  delay (2000);
}
}