public static void main ( String [ ] args ) {
  Scanner input = new Scanner ( System . in ) ;
  int n = input . nextInt ( ) ;
  int m = input . nextInt ( ) ;
  String [ ] s = new String [ n ] ;
  int alreadyBlack = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    s [ i ] = input . next ( ) ;
  }
  int maxx = 0 ;
  int minx = Integer . MAX_VALUE ;
  int maxy = 0 ;
  int miny = Integer . MAX_VALUE ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    for ( int j = 0 ;
    j < m ;
    j ++ ) {
      if ( s [ i ] . charAt ( j ) == 'B' ) {
        alreadyBlack ++ ;
        maxx = Math . max ( maxx , i ) ;
        maxy = Math . max ( maxy , j ) ;
        minx = Math . min ( minx , i ) ;
        miny = Math . min ( miny , j ) ;
      }
    }
  }
  int lenx = maxx - minx + 1 ;
  int leny = maxy - miny + 1 ;
  int len = Math . max ( lenx , leny ) ;
  if ( alreadyBlack == 0 ) {
    System . out . println ( "1" ) ;
  }
  else if ( len > n || len > m ) {
    System . out . println ( "-1" ) ;
  }
  else if ( Math . sqrt ( len * len ) != len ) {
    System . out . println ( "-1" ) ;
  }
  else {
    System . out . println ( len * len - alreadyBlack ) ;
  }
}

public static void main ( String [ ] args ) { Scanner input = new Scanner ( System . in ) ; int n = input . nextInt ( ) ; int m = input . nextInt ( ) ; String [ ] s = new String [ n ] ; int alreadyBlack = 0 ; for ( int i = 0 ; i < n ; i ++ ) { s [ i ] = input . next ( ) ; } int maxx = 0 ; int minx = Integer . MAX_VALUE ; int maxy = 0 ; int miny = Integer . MAX_VALUE ; for ( int i = 0 ; i < n ; i ++ ) { for ( int j = 0 ; j < m ; j ++ ) { if ( s [ i ] . charAt ( j ) == ' B ' ) { alreadyBlack ++ ; maxx = Math . max ( maxx , i ) ; maxy = Math . max ( maxy , j ) ; minx = Math . min ( minx , i ) ; miny = Math . min ( miny , j ) ; } } } int lenx = maxx - minx + 1 ; int leny = maxy - miny + 1 ; int len = Math . max ( lenx , leny ) ; if ( alreadyBlack == 0 ) { System . out . println ( "1" ) ; } else if ( len > n || len > m ) { System . out . println ( " - 1" ) ; } else if ( Math . sqrt ( len * len ) != len ) { System . out . println ( " - 1" ) ; } else { System . out . println ( len * len - alreadyBlack ) ; } }
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name: (identifier) value: (array_creation_expression type: (type_identifier) dimensions: (dimensions_expr (identifier))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (field_access object: (identifier) field: (identifier)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (field_access object: (identifier) field: (identifier)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (array_access array: (identifier) index: (identifier)) name: (identifier) arguments: (argument_list (identifier))) right: (character_literal))) consequence: (block (expression_statement (update_expression (identifier))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (identifier))))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (identifier))))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (identifier))))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (identifier))))))))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (decimal_integer_literal)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (identifier))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list 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name: (identifier) arguments: (argument_list (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (identifier)))))))))))