PROGRAMMING:Programmers buy watermelons

My wife called my husband who was a programmer: "I'll buy 10 steamed buns to bring back when I get off work. If I see a watermelon seller, I'll buy one."
That night, the programmer's husband came into the house with a steamed bun in his hand
The wife says angrily: "how did you buy a steamed bun?"
My husband replied, "because I saw someone selling watermelons.".
Use 'y' to show the watermelon seller, use 'n' to show the watermelon seller. Write a program to judge how many steamed buns the programmer bought today
If the input is neither 'y' nor 'n', the output is' error '
###Input format:
Enter y or N in one line to indicate whether you see a watermelon seller.
###Output format:
For each group of input, output the number of steamed buns or 'error' purchased by the programmer in one line.
###Input example:
Here is a set of inputs. For example:
```in
Y
```
###Output example:
The corresponding output is given here. For example:
```out
one
```
###Input example:
Here is a set of inputs. For example:
```in
N
```
###Output example:
The corresponding output is given here. For example:
```out
ten
```
###Input example:
Here is a set of inputs. For example:
```in
x
```
###Output example:
The corresponding output is given here. For example:
```out
error
```






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