static boolean InvolutoryMatrix ( int mat [ ] [ ] ) {
  int res [ ] [ ] = new int [ N ] [ N ] ;
  multiply ( mat , res ) ;
  for ( int i = 0 ;
  i < N ;
  i ++ ) {
    for ( int j = 0 ;
    j < N ;
    j ++ ) {
      if ( i == j && res [ i ] [ j ] != 1 ) return false ;
      if ( i != j && res [ i ] [ j ] != 0 ) return false ;
    }
  }
  return true ;
}

static boolean InvolutoryMatrix ( int mat [ ] [ ] ) { int res [ ] [ ] = new int [ N ] [ N ] ; multiply ( mat , res ) ; for ( int i = 0 ; i < N ; i ++ ) { for ( int j = 0 ; j < N ; j ++ ) { if ( i == j && res [ i ] [ j ] != 1 ) return false ; if ( i != j && res [ i ] [ j ] != 0 ) return false ; } } return true ; }
(method_declaration (modifiers) type: (boolean_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (integral_type) name: (identifier) dimensions: (dimensions))) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier)) dimensions: (dimensions_expr (identifier))))) (expression_statement (method_invocation name: (identifier) arguments: (argument_list (identifier) (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: (binary_expression left: (identifier) right: (identifier)) right: (binary_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (decimal_integer_literal)))) consequence: (return_statement (false))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (binary_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (decimal_integer_literal)))) consequence: (return_statement (false))))))) (return_statement (true))))