def hex_to_bin(hex_str):
    return bin(int(hex_str, 16))[2:].zfill(len(hex_str) * 4)

def hamming_distance(hex1, hex2):
    b1 = hex_to_bin(hex1)
    b2 = hex_to_bin(hex2)
    return sum(c1 != c2 for c1, c2 in zip(b1, b2))

hash1 = "f6f5431d25bbf28f431ed96532ebafa65bf5931e"
hash2 = "f6f5431d25bbf28dc980f0775c8da0550288275d"

print(hamming_distance(hash1, hash2))