#include<bits/stdc++.h>
using namespace std;

const int mx =1e3+5;
long long a[mx];
long long b[mx];
int n;


long long getstart()
{
    long long l = a[0],r=b[0];
    for (int i=1;i<n;i++)
    {
        if (b[i]>=l && r>=a[i])
        {
            l = max(l,a[i]);
            r = min(r,b[i]);
        }
        else
        {
            if (a[i]>r) return r;
            return l;
        }
    }
    return l;
}

int main()
{
    int t;
    cin>>t;
    while (t--)
    {
        cin>>n;
        for (int i=0;i<n;i++) cin>>a[i]>>b[i];
        long long x1 = getstart();
        long long x2 = x1,ans1=0,ans2=0;
        int flag = 0;
        for (int i=1;i<n;i++)
        {
            if (flag==0)
            {
                if (b[i]<x1||a[i]>x1) flag=1;
            }
            if (flag==1)
            {
                long long x3,x4;
                if (b[i]<x1)
                {
                    x3=b[i];
                    if (a[i]!=b[i]) x4=x3-1;
                    else x4=x3;
                }
                else if (a[i]>x1)
                {
                    x3=a[i];
                    if (a[i]!=b[i]) x4=x3+1;
                    else x4=x3;
                }
                else if (b[i]<x2)
                {
                    x4=b[i];
                    x3=x1;
                }
                else if (a[i]>x2)
                {
                    x4=a[i];
                    x3=x1;
                }
                else
                {
                    x3=x1;
                    x4=x2;
                }
                long long c,d,x,y;
                x=abs(x3-x1);
                y=abs(x3-x2);
                c = x/2 + x%2;
                d = y/2+y%2;
              //  cout<<x<<endl;
                long long temp = min(ans1+c,ans2+d);

                x=abs(x4-x1);
                y= abs(x4-x2);
                c = x/2+x%2;
                d = y/2+y%2;
                ans2 = min(ans1+c,ans2+d);
                ans1 = temp;
                x1=x3;
                x2=x4;
            }
        }
        cout<<min(ans1,ans2)<<endl;
    }
}