public class NestedLoop {
  public static void main(String[] args) {
    int x = 1;
    for (int i = 0; i < 3; i++) {
      System.out.println("");
      for (int k = 1; k <= 4 - i; k++) {
        System.out.print(x);
        x++;
      }
    }
  }
}