#include<stdio.h>
#include<string.h>
#include<vector>
#include<map>
#include<queue>
using namespace std;
struct qujian
{
    int x,y;
}a[150000],b[150000];
struct node
{
    int from;
    int to;
    int w;
    int next;
}e[550000];
int head[150000];
int dist[150000];
int vis[150000];
int n,m,cont;
vector<int>End;
map<int,int>Map;
void add(int from,int to,int w)
{
    //printf("----%d %d %d\n",from,to,w);
    e[cont].to=to;
    e[cont].w=w;
    e[cont].next=head[from];
    head[from]=cont++;
}
int Cal(int x,int y)
{
    if(x<y)swap(x,y);
    if((x-y)%2==0)return (x-y)/2;
    else return (x-y)/2+1;
}
void SPFA()
{
    queue<int>s;
    for(int i=1;i<=n;i++)
    {
        if(dist[i]==0)s.push(i);
    }

    while(!s.empty())
    {
        int u=s.front();
        vis[u]=0;
        s.pop();
        for(int i=head[u];i!=-1;i=e[i].next)
        {
            int v=e[i].to;
            int w=e[i].w;
            if(dist[v]>dist[u]+w)
            {
                dist[v]=dist[u]+w;
                if(vis[v]==0)
                {
                    s.push(v);
                    vis[v]=1;
                }
            }
        }
    }
    int ans=2000000000;
    for(int i=0;i<End.size();i++)
    {
        ans=min(ans,dist[End[i]]);
    }
    printf("%d\n",ans);
}
int main()
{
    int t;scanf("%d",&t);
    while(t--)
    {
        memset(vis,0,sizeof(vis));
        End.clear();
        Map.clear();
        n=0;
        cont=0;
        memset(head,-1,sizeof(head));
        int qqq;scanf("%d",&qqq);
        for(int i=1;i<=qqq;i++)
        {
            scanf("%d%d",&a[i].x,&a[i].y);
        }
        int cnt=0;
        for(int i=1;i<=qqq;i++)
        {
            if(i==1)
            {
                b[cnt].x=a[i].x;
                b[cnt++].y=a[i].y;
            }
            else
            {
                bool flag=0;
                if(a[i].x<=b[cnt-1].x && a[i].y>=b[cnt-1].x)
                {
                    flag=1;
                }
                if(a[i].x>=b[cnt-1].x&&a[i].x<=b[cnt-1].y)
                {
                    flag=1;
                }
                if(flag==1)
                {
                    int maxn=max(a[i].x,b[cnt-1].x);
                    int minn=min(a[i].y,b[cnt-1].y);
                    b[cnt-1].x=maxn;
                    b[cnt-1].y=minn;
                }
                else
                {
                    b[cnt].x=a[i].x;
                    b[cnt].y=a[i].y;
                    cnt++;
                }
            }
        }
        qqq=cnt;
        for(int i=0;i<cnt;i++)
        {
            a[i+1].x=b[i].x;
            a[i+1].y=b[i].y;
        }
        for(int i=1;i<=qqq*5;i++)dist[i]=2000000000;
        if(qqq==1)
        {
            printf("0\n");
            continue;
        }
        for(int i=1;i<qqq;i++)
        {
            vector<int>s;
            vector<int>q;
            s.push_back(a[i].x);
            if(a[i].x+1<a[i].y)s.push_back(a[i].x+1);
            if(a[i].y-1>a[i].x)s.push_back(a[i].y-1);
            if(a[i].x!=a[i].y)s.push_back(a[i].y);
            q.push_back(a[i+1].x);
            if(a[i+1].x+1<a[i+1].y)q.push_back(a[i+1].x+1);
            if(a[i+1].y-1>a[i+1].x)q.push_back(a[i+1].y-1);
            if(a[i+1].x!=a[i+1].y)q.push_back(a[i+1].y);
            //printf("-%d %d\n",s.size(),q.size());
            if(i==1)for(int j=0;j<s.size();j++)Map[s[j]]=++n;
            for(int j=0;j<q.size();j++)Map[q[j]]=++n;
            for(int j=0;j<s.size();j++)
            {
                int u=Map[s[j]];
                for(int k=0;k<q.size();k++)
                {
                    int v=Map[q[k]];
                    add(u,v,Cal(s[j],q[k]));
                }
            }
            if(i==1)
            {
                for(int j=0;j<s.size();j++)
                {
                    //printf("yes");
                    dist[Map[s[j]]]=0;
                }
            }
            if(i==qqq-1)
            {
                for(int j=0;j<q.size();j++)
                {
                    End.push_back(Map[q[j]]);
                }
            }
        };
        SPFA();
    }
}