source_code: import java.util.Scanner;
  
  public class MargariteBestPresent_1080B {
  
  	private static int f(int x) {
  		return (x%2==0)?x/2:(x-1)/2-x;
  	}
  	
  	public static void main(String[] args) {
  		Scanner sc = new Scanner(System.in);
  		int n,r,l;
  		n = sc.nextInt();
  		while(n-->0) {
  			l = sc.nextInt();
  			r = sc.nextInt();
  
  			System.out.println(f(r)-f(l-1));
  		}
  		sc.close();
  	}
  
  }
  