public static void main ( String [ ] args ) throws Exception {
  int nm [ ] = in . readA ( ) ;
  int n = nm [ 0 ] , m = nm [ 1 ] ;
  char [ ] [ ] board = new char [ n ] [ m ] ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    char [ ] line = in . readLine ( ) . toCharArray ( ) ;
    for ( int j = 0 ;
    j < m ;
    j ++ ) {
      board [ i ] [ j ] = line [ j ] ;
    }
  }
  boolean possible = true ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    for ( int j = 0 ;
    j < m ;
    j ++ ) {
      possible = possible && check ( i , j , board [ i ] [ j ] , board ) ;
    }
  }
  if ( ! possible ) System . out . println ( "NO" ) ;
  else System . out . println ( "YES" ) ;
}

public static void main ( String [ ] args ) throws Exception { int nm [ ] = in . readA ( ) ; int n = nm [ 0 ] , m = nm [ 1 ] ; char [ ] [ ] board = new char [ n ] [ m ] ; for ( int i = 0 ; i < n ; i ++ ) { char [ ] line = in . readLine ( ) . toCharArray ( ) ; for ( int j = 0 ; j < m ; j ++ ) { board [ i ] [ j ] = line [ j ] ; } } boolean possible = true ; for ( int i = 0 ; i < n ; i ++ ) { for ( int j = 0 ; j < m ; j ++ ) { possible = possible && check ( i , j , board [ i ] [ j ] , board ) ; } } if ( ! possible ) System . out . println ( " NO " ) ; else System . out . println ( " YES " ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) (throws (type_identifier)) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) dimensions: (dimensions) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (array_access array: (identifier) index: (decimal_integer_literal))) declarator: (variable_declarator name: (identifier) value: (array_access array: (identifier) index: (decimal_integer_literal)))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier)) dimensions: (dimensions_expr (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 (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) name: (identifier) arguments: (argument_list)))) (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: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (array_access array: (identifier) index: (identifier)))))))) (local_variable_declaration type: (boolean_type) declarator: (variable_declarator name: (identifier) value: (true))) (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 (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (method_invocation name: (identifier) arguments: (argument_list (identifier) (identifier) (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) (identifier)))))))))) (if_statement condition: (parenthesized_expression (unary_expression operand: (identifier))) consequence: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))) alternative: (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (string_literal)))))))