Lucky and Arrays

Lucky has an array of N elements [a1, a2, a3, ....,an]. Bunny decided to play a game with the array. So he gave another array which have N elements [b1, b2, b3, ...., bn] and ask her to find the minimum number of bits required to change ai to bi. Let's consider ai = 4 and bi = 3 binary values of 4 and 3 are 100 and 011, we need 3 bits to change 4 to 3. She needs your help to solve this problem.