PROGRAMMING:Alphabetic figure

Problem description
Letters can be used to form some beautiful figures. Here is an example:
ABCDEFG
BABCDEF
CBABCDE
DCBABCD
EDCBABC
This is a graph with 5 rows and 7 columns. Please find out the rule of this graph and output a graph with n rows and m columns.
###Input format:
Input a row, including two integers n and m, which respectively represent the number of rows and columns of the graph you want to output. Data scale and agreement
1 <= n, m <= 26。
###Output format:
Output n lines, each M characters, for your graphics.
###Input example:
Here is a set of inputs. For example:
```in
5 7
```
###Output example:
The corresponding output is given here. For example:
```out
ABCDEFG
BABCDEF
CBABCDE
DCBABCD
EDCBABC
```







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