编程题：成绩等级(*)

请编写程序，根据学生的分数确定其等级。

<table>
<tr>
<td align = "center"><b>分数</b></td>
<td align = "center"><b>等级</b></td>
</tr>
<tr>
<td align = "center">[90, 100]</td>
<td align = "center">A</td>
</tr>
<tr>
<td align = "center">[80, 90)</td>
<td align = "center">B</td>
</tr>
<tr>
<td align = "center">[70, 80)</td>
<td align = "center">C</td>
</tr>
<tr>
<td align = "center">[60, 70)</td>
<td align = "center">D</td>
</tr>
<tr>
<td align = "center">[0, 60)</td>
<td align = "center">E</td>
</tr>
</table>

#### 输入格式
> 成绩

#### 输出格式
> 等级

#### 输入样例
in
87.5


#### 输出样例
out
B








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