#include <bits/stdc++.h> using namespace std; int main() { int n; cin>>n; int a[n],b[n]; for(int i = 0;i < n;i++) { cin>>a[i]>>b[i]; int temp = 0; for(int j = a[i];j <= b[i];j++) { if(j % 2 == 1) { temp += j * -1; } else { temp += j; } } cout<<temp<<endl; } return 0; }