#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <ctime>
#include <cmath>
using namespace std;
int a[1020];
int b[1020];
int ans1, ans2;
//int ans;
int get_gcd(int x,int y){
    if(x < y)swap(x,y);
    while(x % y > 0){
        int k = x % y;
        x = y;
        y = k;
    }
    return y;
}
void get_ans(int x){
    if(a[x] == 0 && b[x] == 0){
        get_ans(x-1);
        return;
    }
    
    if(a[x] == 0){
        ans1 = 0;
        ans2 = 1;
        return;
    }else if(b[x] == 0){
        ans1 = 1;
        ans2 = 0;        
    }else{
        int y = get_gcd(a[x], b[x]);
        ans1 = a[x] / y;
        ans2 = b[x] / y;
    }
}
int main(){
    
    int T;
    scanf("%d",&T);
    for(int ii=1;ii<=T;++ii){
        int n;
        scanf("%d",&n);
        for(int i=1;i<=n;++i){
            scanf("%d%d",&a[i], &b[i]);
        }
        int ans = 0;
        int nowL = a[1];
        int nowR = b[1];
        int now;
        for(now = 2; now <= n; ++now){
            if(nowL > b[now] || nowR < a[now]){
                break;
            }else{
                nowL = max(nowL, a[now]);
                nowR = min(nowR, b[now]);
            }
        }//choose start
        
        int now_wz = 0;
        if(now <= n){
            if(nowL > a[now]) now_wz = nowL;else now_wz = nowR;
        }
        
        for(;now<=n;++now){
            if(now_wz > b[now]){
                int distance = abs(now_wz - b[now]);
                if(now < n && (distance % 2 == 1) && a[now] < b[now]){
                    int p = now + 1;
                    while(p <= n){
                        if(b[now] <= b[p] && b[now] >= a[p]) ++ p;
                        else break;
                    }
                    if(p <= n && b[p] < b[now]) ++ distance;
                }
                ans += (distance + 1) / 2;
                now_wz = now_wz - distance;
            }else if(now_wz < a[now]){
                int distance = abs(now_wz - a[now]);
                if(now < n && (distance % 2 == 1) && a[now] < b[now]){
                    int p = now + 1;
                    while(p <= n){
                        if(a[now] <= b[p] && a[now] >= a[p]) ++ p;
                        else break;
                    }
                    if(p <= n && a[p] > a[now]) ++ distance;
                }
                ans += (distance + 1) / 2;
                now_wz = now_wz + distance;                
            }
        } 
        
        cout << ans << endl;
    }
    return 0;
}