n=gets.to_i-1
a,b=$<.map{|e|e.split.map &:to_i}.transpose
sa,sb=[a,b].map(&:sum)
p (0..10**6).count{|x|
	x+sa-sb>=0 && x<=sb && (0...n).all?{|i|
		a[i]+b[i]<=x+sa
	}
}