# coding: utf-8 import array, bisect, collections, copy, heapq, itertools, math, random, re, string, sys, time sys.setrecursionlimit(10 ** 7) INF = 10 ** 20 MOD = 10 ** 9 + 7 def II(): return int(input()) def ILI(): return list(map(int, input().split())) def IAI(LINE): return [ILI() for __ in range(LINE)] def IDI(): return {key: value for key, value in ILI()} def read(): x, y, d = ILI() return (x, y, d) def solve(x, y, d): ans = 0 if d > x + y or d < 0: ans = 0 elif x <= d <= x + y: height = d - x if x >= height: ans = y - height + 1 else: ans = x + 1 elif 0 <= d < x: width = d if y >= width: ans = width + 1 else: ans = y + 1 return ans def main(): params = read() print(solve(*params)) if __name__ == "__main__": main()