Marsha adds all but one of the first ten positive integers. Her sum is a square number. Which one of the first ten positive integers did Marsha not include?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Marsha adds all but one of the first ten positive integers. Her sum is a square number. Which one of the first ten positive integers did Marsha not include?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
6
Marsha adds all but one of the first ten positive integers. Her sum is a square number. Which one of the first ten positive integers did Marsha not include?
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