#include<bits/stdc++.h>
#define maxn 3050
using namespace std;

const int inf=1<<30;

int n,m;
int a[maxn],b[maxn];

int dis(int a,int b)    {
    int d=abs(a-b);
    return (d+1)/2;
}

void insect(int l1,int r1,int l2,int r2,int &l,int &r)    {
    l=max(l1,l2);
    r=min(r1,r2);
}

int main()    {
//    freopen("c.in","r",stdin);
    int T;
    scanf("%d",&T);
    while (T--)    {
        scanf("%d",&n);
        for (int i=1;i<=n;++i)
            scanf("%d%d",a+i,b+i);
        int l=a[1],r=b[1],ans=0;
        for (int i=2;i<=n;++i)    {
            if (b[i]<l)    { 
                ans+=dis(b[i],l);
                if ((l-b[i])&1)
                    l=max(a[i],b[i]-1),r=b[i]; 
                else
                    l=r=b[i];
            } 
            else
            if (r<a[i])    { 
                ans+=dis(r,a[i]);
                if ((a[i]-r)&1)
                    r=min(a[i]+1,b[i]),l=a[i];
                else
                    l=r=a[i];
            } 
            else    {
                insect(l,r,a[i],b[i],l,r);
            }
//            cout<<l<<" "<<r<<" "<<ans<<endl;
        }
        printf("%d\n",ans);
    }
    return 0;
}