What is the complexity to break second preimage resistance?

In the context an of hash functions we have three required properties.

1. Preimage resistance
2. Second preimage resistance
3. Collision resistance.

The bounds for Pre image collision is $O(2^{n-1})$, the bounds for collision resistance is $2^{n/2}$, what are the bounds for breaking second preimage resistance?

Edited to reflect comment by otus. Preimage attack takes $O(2^{n})$ hash function calls on average.
Second preimage attack takes just one extra call so the complexity is essentially the same as that of the preimage attack. Given $x$ you want $x'\neq x$ such that $H(x)=H(x').$ So evaluate $H(x)$ for one extra query, and then apply the preimage attack to $y=H(x).$