#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;



int main()
{
    int t,i,j,k,n,m,st,en,a,b,c,d;
    cin>>t;
    while(t--)
    {
        cin>>m;
        vector<pair<int,int> >v,res;
        while(true)
        {
            cin>>a>>b;
            if(a==0 && b==0)
                break;
            v.push_back(make_pair(a,b));

        }
        sort(v.begin(),v.end());

        st=0,en=0,i=0;
        while(true)
        {
            pair<int,int>p={0,0};
            int flag=0;
            while(i<v.size() && v[i].first<=st)
            {
                flag=1;
                if(p.second<v[i].second)
                    p=v[i];
                en=max(en,p.second);
                i++;
            }
            if(!flag)
            {
                res.clear();
                break;
            }
            res.push_back(p);
            st=en;
            if(en>=m)
                break;
        }
        if(res.size()==0){
            cout<<0<<endl;
        cout<<endl;
        }
        else
        {
            cout<<res.size()<<endl;
            for(i=0;i<res.size();i++)
                cout<<res[i].first<<" "<<res[i].second<<endl;
            cout<<endl;
        }
        v.clear();
    }
    return 0;
}