#include <cstdio>
#include <algorithm>
using namespace std;
struct kdq
{
    int start,end;//起始和结束房间号对应的走廊距离
    bool visit;//判断是否已经计算
}time[505];
bool cmp(kdq a,kdq b)
{
    return a.start<b.start;
}
int main()
{
    int i,j,k,l,n,m;
    int T;
    cin>>T;
    int a,b;
    while(T--)
    {
        cin>>n;
        for(i=0;i<n;i++)
        {
            scanf("%d%d",&a,&b);
            a=(a+1)/2,b=(b+1)/2;//房间号对应的走廊距离
            time[i].start=a<b?a:b;
            time[i].end=a>b?a:b;
            time[i].visit=0;
        }
        sort(time,time+n,cmp);//按start从小到大排序
        int start=time[0].end;
        time[0].visit=1;
        int num=0;
        while(1)//贪心
        {
            num++;
            bool flag=0;
            for(i=0;i<n;i++)
            {
                if(!time[i].visit)
                {
                    if(time[i].start>start)
                    {
                        time[i].visit=1;
                        start=time[i].end;
                    }
                }
            }
            for(i=0;i<n;i++)
            {
                if(!time[i].visit)
                {
                    flag=1;
                    start=time[i].end;
                    time[i].visit=1;
                    break;
                }
            }

            if(!flag)
            break;
        }
        cout<<num*10<<endl;
    }
    return 0;
}