Problem:
Score : 1000 points

Problem Statement

You have two strings A = A_1 A_2 ... A_n and B = B_1 B_2 ... B_n of the same length consisting of 0 and 1.

You can transform A using the following operations in any order and as many times as you want:

Shift A by one character to the left (i.e., if A = A_1 A_2 ... A_n, replace A with A_2 A_3 ... A_n A_1).

Shift A by one character to the right (i.e., if A = A_1 A_2 ... A_n, replace A with A_n A_1 A_2 ... A_{n-1}).

Choose any i such that B_i = 1. Flip A_i (i.e., set A_i = 1 - A_i).

You goal is to make strings A and B equal.

Print the smallest number of operations required to achieve this, or -1 if the goal is unreachable.

Constraints

1 \leq |A| = |B| \leq 2,000

A and B consist of 0 and 1.

Input

Input is given from Standard Input in the following format:

A
B

Output

Print the smallest number of operations required to make strings A and B equal, or -1 if the goal is unreachable.

Sample Input 1

1010
1100

Sample Output 1

3

Here is one fastest way to achieve the goal:

Flip A_1: A = 0010

Shift A to the left: A = 0100

Flip A_1 again: A = 1100

Sample Input 2

1
0

Sample Output 2

-1

There is no way to flip the only bit in A.

Sample Input 3

11010
10001

Sample Output 3

4

Here is one fastest way to achieve the goal:

Shift A to the right: A = 01101

Flip A_5: A = 01100

Shift A to the left: A = 11000

Shift A to the left again: A = 10001

Sample Input 4

0100100
1111111

Sample Output 4

5

Flip A_1, A_3, A_4, A_6 and A_7 in any order.

Solution in Kotlin (1.0.0) (judge verdict: Wrong Answer)

fun main(args: Array<String>) {
    val a = readLine()!!.map { it == '1' }.toBooleanArray()
    val b = readLine()!!.map { it == '1' }.toBooleanArray()
    fun f(i: Int) = (i + a.size) % a.size
    if (b.all { !it }) {
        println(-1)
        return
    }
    val left = IntArray(a.size)
    val right = IntArray(a.size)
    var t = b.lastIndexOf(true)
    for (i in left.indices) {
        left[i] = if (b[i]) 0 else t + 1
        t = left[i]
    }
    t = b.indexOf(true)
    for (i in right.indices.reversed()) {
        right[i] = if (b[i]) 0 else t + 1
        t = right[i]
    }
    var res = a.size * 5
    for (sh in -a.size..a.size) {
        val flip = a.indices
                .filter { a[it] != b[f(it + sh)] }
                .map {
                    Pair(
                        Math.min(left[it], Math.max(left[it] + sh, 0)),
                        Math.min(right[it], Math.max(right[it] - sh, 0))
                    )
                }
                .toTypedArray()
                .sortedBy { -it.first }
        var shifts = 0
        if (!flip.isEmpty()) {
            shifts = flip[0].first
            var tRight = flip[0].second
            for ((pLeft, pRight) in flip.drop(1)) {
                shifts = Math.min(shifts, tRight + pLeft)
                tRight = Math.max(tRight, pRight)
            }
        }
        res = Math.min(res, shifts + flip.size + Math.abs(sh))
    }
    println(res)
}