# Where is the error?

I am performing the following steps to prove $-1 = 1:$

1. $-1 = i^{2}$
2. $-1=i \times i$
3. $-1 = \sqrt{-1} \times \sqrt{-1}$
4. $-1 =\sqrt{-1 \times -1}$
5. $-1 =\sqrt{1}$
6. $-1=1.$

In which step does the error first appear?

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