#include<stdio.h>
#include<string>
using namespace std;
int a[1005],b[1005];
bool cross(int t){
    int len=max(b[t],b[t-1])-min(a[t],a[t-1])+1,len1=b[t]-a[t]+1,len2=b[t-1]-a[t-1]+1;
    return len<len1+len2;
}
int main(){
    int t;
    scanf("%d",&t);
    while(t--){
        int n;
        scanf("%d",&n);
        int cnt=1,tot=0;
        for(int i=0;i<n;i++){
            scanf("%d%d",&a[cnt],&b[cnt]);
            if(cnt>1){
                if(cross(cnt)){
                    a[cnt-1]=max(a[cnt],a[cnt-1]);
                    b[cnt-1]=min(b[cnt],b[cnt-1]);
                    cnt--;
                }
            }
            cnt++;
        }
        long long ans=0;
        if(cnt==1)printf("0\n");
        else{
            if(a[1]>b[2])tot=a[1];
            if(b[1]<a[2])tot=b[1];
            for(int i=1;i<cnt-1;i++){
                if(tot<a[i+1]){
                    ans+=1LL*(a[i+1]-tot+1)/2;
                    
                    if((a[i+1]-tot)%2&&i+2<cnt&&a[i+1]<b[i+1]&&a[i+2]>b[i+1])tot=a[i+1]+1;
                    else tot=a[i+1];
                }
                else {
                    ans+=1LL*(tot-b[i+1]+1)/2;
                    
                    if((tot-b[i+1])%2&&i+2<cnt&&a[i+1]<b[i+1]&&b[i+2]<a[i+1])tot=b[i+1]-1;
                    else tot=b[i+1];
                }
            }
            printf("%I64d\n",ans);
        }
    }
}