func main()
	var ss: [][]char :: cui@input().split(" ")
	var x: int :: ss[0].toInt(&)
	var y: int :: ss[1].toInt(&)
	var d: int :: ss[2].toInt(&)
	var ans: int :: 0
	if(x > d)
		if(y > d)
			do ans :: d + 1
		else
			do ans :: y + 1
		end if
	else
		if(y > d)
			do ans :: x + 1
		else
			do ans :: [0, y - (d - x) + 1].max()
		end if
	end if
	do cui@print("\{ans}\n")
end func