int a=2, b=3, c=4, d=5, e=6, f=7, g=8;
void setup() {
  for(int led = 2; led <=8; led++)
      pinMode(led, OUTPUT);
}

void loop() {
  segment(1, 1, 1, 1, 1, 1, 0); // 0
  segment(0, 1, 1, 0, 0, 0, 0); // 1
  segment(1, 1, 0, 1, 1, 0, 1); // 2
  segment(1, 1, 1, 1, 0, 0, 1); // 3
}
void segment(bool A, bool B, bool C,
      bool D, bool E, bool F, bool G){
  digitalWrite(a, A);
  digitalWrite(b, B);
  digitalWrite(c, C);
  digitalWrite(d, D);
  digitalWrite(e, E);
  digitalWrite(f, F); 
  digitalWrite(g, G);delay(1000);
}