Problem Statement  
Given two matrices a and b, both composed of zeroes and ones, return the minimal number of operations necessary to transform matrix a into matrix b. An operation consists of flipping (one becomes zero and zero becomes one) all elements of some contiguous 3 x 3 submatrix. If a cannot be transformed into b, return 1.  
Definition  
 
Constraints  
  a will contain between 1 and 50 elements, inclusive.  
  a and b will contain the same number of elements.  
  Each element of a will contain between 1 and 50 characters, inclusive.  
  Each element of b will contain between 1 and 50 characters, inclusive.  
  All elements of a and b will contain the same number of characters.  
  Each element of a and b will be contain only zeroes ('0') and ones ('1').  
Examples  
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