line = input().split(" ")

# 休み
holiday1 = int(line[0])
holiday2 = int(line[1])
# 計測終了日
endAt = int(line[2])

i = 1
cnt = 0
while i <= endAt:

    if (i in (holiday1, holiday2)):
        i += 1
        continue
    i += 1
    cnt += 1
    
print(cnt)