PROGRAMMING:Chenyang brother's consideration

Chenyang brother's girlfriend one day suddenly thought that she wanted to write down the leap year that she and he could spend together in their lifetime, so she counted from the year they were together, and wrote down every leap year that they could spend together since then. How long their lifetime is. The considerate Chenyang elder brother doesn't want to make his girlfriend write one by one. He says that he can write a program for her. As long as he inputs two integers, he can output the leap year of the period. But mischievous she dislikes the program output has no format, ugly dead. The powerful Chenyang brother said what kind of format can defeat me, as long as you want, I can let it output. Chenyang brother's girlfriend doesn't want to embarrass him, so she wants to lose a right triangle (one in the first line, two in the second line,..., and so on). If this is your girlfriend, little acmer, can you do it?
###Input format:
There are several groups of test data, which are processed to the end of the file. Enter two integers a and B.
###Output format:
Output the leap year in the interval [a, b], there are spaces between two years in the same line, and output in the form of right triangle (one in the first line, two in the second line,..., and so on).
The output of each group is empty.
###Input example:
Here is a set of inputs. For example:
```in
2000 2030
```
###Output example:
The corresponding output is given here. For example:
```out
two thousand
2004 2008
2012 2016 2020
2024 2028
```







answer：If there is no answer, please comment