eolymp
bolt
Try our new interface for solving problems
Problems

Bits Equalizer

Bits Equalizer

You are given two non-empty strings S and T of equal lengths. S contains the characters 0, 1 and ?, whereas T contains 0 and 1 only. Your task is to convert S into T in minimum number of moves. In each move, you can

  1. change a 0 in S to 1
  2. change a ? in S to 0 or 1
  3. swap any two characters in S

As an example, suppose S = "01??00" and T = "001010". We can transform S into T in 3 moves:

  • Initially S = "01??00"
  • Move 1 – change S2 to 1. S becomes "011?00"
  • Move 2 – change S3 to 0. S becomes "011000"
  • Move 3 – swap S1 with S4. S becomes "001010"
  • S is now equal to T

Input

The first line is an integer c (c200) that indicates the number of test cases. Each case consists of two lines. The first line is the string S consisting of 0, 1 and ?. The second line is the string T consisting of 0 and 1. The lengths of the strings won't be larger than 100.

Output

For each case, output the case number first followed by the minimum number of moves required to convert S into T. If the transition is impossible, output -1 instead.

Time limit 1 second
Memory limit 128 MiB
Input example #1
3
01??00
001010
01
10
110001
000000
Output example #1
Case 1: 3
Case 2: 1
Case 3: -1
Source 2012 ACM Southwestern European Regional Programming Contest (SWERC), Problem B