static int findS ( int s ) {
  int l = 1 , r = ( s / 2 ) + 1 ;
  while ( l <= r ) {
    int mid = ( l + r ) / 2 ;
    int sum = mid * ( mid + 1 ) / 2 ;
    if ( sum == s ) return mid ;
    else if ( sum > s ) r = mid - 1 ;
    else l = mid + 1 ;
  }
  return - 1 ;
}

static int findS ( int s ) { int l = 1 , r = ( s / 2 ) + 1 ; while ( l <= r ) { int mid = ( l + r ) / 2 ; int sum = mid * ( mid + 1 ) / 2 ; if ( sum == s ) return mid ; else if ( sum > s ) r = mid - 1 ; else l = mid + 1 ; } return - 1 ; }
(method_declaration (modifiers) type: (integral_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (integral_type) name: (identifier))) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (decimal_integer_literal)))) (while_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (parenthesized_expression (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: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal)))) right: (decimal_integer_literal)))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) consequence: (return_statement (identifier)) alternative: (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) consequence: (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))) alternative: (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))))))) (return_statement (unary_expression operand: (decimal_integer_literal)))))