public static void main ( String [ ] args ) {
  FastScanner fs = new FastScanner ( ) ;
  char [ ] s = fs . next ( ) . toCharArray ( ) ;
  int lucky = 0 ;
  for ( char c : s ) {
    if ( c == '4' || c == '7' ) {
      lucky ++ ;
    }
  }
  System . out . println ( ( lucky == 4 || lucky == 7 ) ? "YES" : "NO" ) ;
}

public static void main ( String [ ] args ) { FastScanner fs = new FastScanner ( ) ; char [ ] s = fs . next ( ) . toCharArray ( ) ; int lucky = 0 ; for ( char c : s ) { if ( c == '4' || c == '7' ) { lucky ++ ; } } System . out . println ( ( lucky == 4 || lucky == 7 ) ? " YES " : " NO " ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list)))) (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)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (enhanced_for_statement type: (integral_type) name: (identifier) value: (identifier) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (character_literal)) right: (binary_expression left: (identifier) right: (character_literal)))) consequence: (block (expression_statement (update_expression (identifier))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (ternary_expression condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))) consequence: (string_literal) alternative: (string_literal)))))))