import java.util.Scanner; public class Main { public static void main(String [] args) { int T,n,a,b; int max,temp; Scanner in =new Scanner(System.in); T=in.nextInt(); while(T!=0) { max=0; temp=0; n=in.nextInt(); while(n!=0) { a=in.nextInt(); b=in.nextInt(); temp=temp-a+b; if(max