How many equivalence classes does this equivalence relation have?

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Let Σ={0,1}, ≡L is an equivalence relation for set L Let s = 10100 and L = {s} be the language containing only string s

L−x = {y:xy∈L}

x ≡L y ⟺ L−x = L−y

I can count 6:

L-empty

L-1

L-10

L-101

L-1010

L-10100

However I believe the there should be 7 states here. Can anyone point out what I'm missing please? What would "the partition of Σ∗ in the equivalence classes of ≡L." be then?

Thanks for any help!