package main

import "fmt"

func main() {
	var q int
	fmt.Scan(&q)
	for i := 0; i < q; i++ {
		var l, r int
		fmt.Scan(&l, &r)
		sum, length := 0, r-l+1
		if l%2 == 0 {
			sum -= length / 2
		} else {
			sum += length / 2
		}
		if length%2 == 1 {
			if r%2 == 1 {
				sum -= r
			} else {
				sum += r
			}
		}
		fmt.Println(sum)
	}
}