1520
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Given the square of an integer $x$ is 1521, what is the value of $(x+1)(x-1)$?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
1520
Given the square of an integer $x$ is 1521, what is the value of $(x+1)(x-1)$?
train