int_data = input()

sp_int = int_data.split(" ")

first_sab = int(sp_int[0])
sec_sab = int(sp_int[1])
las_day = int(sp_int[2])

che_day = 1
result = 0

while(che_day <= las_day):
	if che_day != first_sab and che_day != sec_sab:
		result = result + 1

	che_day = che_day + 1

print(result)