<|im_start|>system
You are a helpful assistant. You first think about the reasoning process in the mind and then provide the user with the answer. You should try to truely solve the question by yourself without cheating.  <|im_end|>
<|im_start|>user
 A two-digit number is considered an "odd-sum number" if, when its digits are reversed (with the result still being a two-digit number), the sum of the new number and the original number contains no even digits. Determine how many two-digit odd-sum numbers there are. Show your work in <think> </think> tags. And return the final answer in <answer> </answer> tags.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>
user
20
A two-digit number is considered an "odd-sum number" if, when its digits are reversed (with the result still being a two-digit number), the sum of the new number and the original number contains no even digits. Determine how many two-digit odd-sum numbers there are.
test