public static void main ( String [ ] args ) {
  int n = sc . nextInt ( ) ;
  int k = ( int ) Math . sqrt ( 2 * n ) ;
  while ( true ) {
    int sum = ( 1 + k ) * k / 2 ;
    if ( sum < n ) ++ k ;
    else break ;
  }
  System . out . println ( k ) ;
}

public static void main ( String [ ] args ) { int n = sc . nextInt ( ) ; int k = ( int ) Math . sqrt ( 2 * n ) ; while ( true ) { int sum = ( 1 + k ) * k / 2 ; if ( sum < n ) ++ k ; else break ; } System . out . println ( k ) ; }
(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: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (cast_expression type: (integral_type) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (decimal_integer_literal) right: (identifier))))))) (while_statement condition: (parenthesized_expression (true)) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (binary_expression left: (parenthesized_expression (binary_expression left: (decimal_integer_literal) right: (identifier))) right: (identifier)) right: (decimal_integer_literal)))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) consequence: (expression_statement (update_expression (identifier))) alternative: (break_statement)))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))