1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 #define maxn 6000000 5 using namespace std; 6  7 int t,m; 8 int t1; 9 int ll[maxn],rr[maxn];10 struct node11 {12     int l,r;13     int id;14     bool operator <(const node &a)const15     {16         return (l<a.l)||(l==a.l&&r>a.r);17     }18 } p[maxn],ans[maxn];19 20 int main()21 {22     scanf("%d",&t);23     while(t--)24     {25         t1=0;26         scanf("%d",&m);27         int cnt=0;28         int l,r;29         int num=0;30         while(scanf("%d%d",&l,&r)!=EOF)31         {32             if(l==0&&r==0) break;33             if(l>m||r<0) continue;34             p[cnt].id=num;35             p[cnt].l=l;36             p[cnt++].r=r;37         }38         sort(p,p+cnt);39         bool flag1=false;40         int ll=0,rr=0;41         while(1)42         {43             if(ll>=m)44             {45                 break;46             }47             flag1=false;48             rr=0;49             int pos;50             for(int i=0; i<cnt; i++)51             {52                 if(p[i].l<=ll&&p[i].r>rr)53                 {54                     pos=i;55                     rr=p[i].r;56                     flag1=true;57                 }58             }59             if(flag1)60             {61                t1++;62                ans[t1]=p[pos];63                ll=rr;64             }65             else break;66         }67         if(flag1)68         {69             printf("%d\n",t1);70             for(int i=1; i<=t1; i++)71             {72                 printf("%d %d\n",ans[i].l,ans[i].r);73             }74         }75         else printf("0\n");76     }77     return 0;78 }