#lang racket

(require math/number-theory)

(define (solution)
  (define a (read))
  (define b (read))
  (define t (read))
  
  (with-modulus 1000000007 (modexpt (/ (+ a b) 2) t)))

(module+ main (solution))

(module+ test
  (with-input-from-string "2 4 1" solution)
  (with-input-from-string "2 4 1000000000000000000" solution))