In order to find five matching outputs from a 512 bit hash function, an attacker needs to compute how many hash operations they must perform.
I tried to solve this question. I used the approach of birthday paradox and came to a conclusion of 2^256 operations. But here the condition has been modified to finding five matching outputs. For this I first found operations for 1st pair of matching output i.e. 2^256, then 2 and 3, 3 and 4, 4 and 5. Doing so, I got finally 4* 2^256.
Is this correct or any better solution?