#include <cstdio>
#include <algorithm>
using namespace std;
const int N = 1000 + 10;
int n;
int l[N], r[N];
int ll, rr;
int main(){
    int T;
    scanf("%d", &T);
    while(T --){
        scanf("%d", &n);
        for(int i = 0; i < n; ++ i){
            scanf("%d%d", &l[i], &r[i]);
        }
        ll = l[0];
        rr = r[0];
        int f = 0;
        int ans = 0;
        if(ll == rr){
            f = 1;
        }
        for(int i = 1; i < n; ++ i){
            if(f == 0 && ll != rr){
                if(rr >= l[i] && r[i] >= ll){
                    ll = max(ll, l[i]);
                    rr = min(rr, r[i]);
                    if(ll == rr){
                        f = 1;
                    }
                    continue;
                }
                else{
                    if(ll - r[i] >= l[i] - rr){
                        f = 1;
                    }
                    else{
                        ll = rr;
                        f = 1;
                    }

                }
            }
            if(l[i] - ll > 0){
                if((l[i] - ll) % 2 == 0){
                    
                    ans += (l[i] - ll) / 2;
                    ll = l[i];
                }
                else{
                    ans += (l[i] - ll) / 2;
                    ll = l[i];
                    
                    ans += (l[i] - ll) / 2 + 1;
                    ll = l[i];
                    if(r[i] != l[i]){
                        rr = ll+1;
                        f = 0;
                    }
                }
            }
            else if(ll - r[i] > 0){
                if((ll - r[i]) % 2 == 0){
                    
                    ans += (ll - r[i]) / 2;
                    ll = r[i];
                }
                else{

                    ans += (ll - r[i]) / 2 + 1;
                    ll = r[i];
                    if(r[i] != l[i]){
                        rr = ll;
                        ll = rr - 1;
                        f = 0;
                    }

                    
                }
            }
            else if(l[i] == r[i]){
                ll = l[i];
                f = 1;
            }

        }
        printf("%d\n", ans);
    }
}