#include <iostream>

 #include <cstdio>

 #include <cmath>

 #include <cstring>

 #include <algorithm>

 #define  eps 1e-8

 using namespace std;

 struct  point{

     double x,y;

 };

 point p[],stack[];

 int N,top;

 double multi(point p1, point p2, point p3){   //向量(p1->p2)^(p1->p3)

     return (p2.x - p1.x) * (p3.y - p1.y) - (p2.y - p1.y) * (p3.x - p1.x);

 }

 double dis(point a, point b){

     return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));

 }

 int cmp(const void *a, const void *b){    //按极角排序

     point c = *(point *)a;

     point d = *(point *)b;

     double k = multi(p[], c, d);

     if(k <  || (!k && dis(c, p[]) > dis(d, p[])))   return ;

     return -;

 }

 void Convex(){    //凸包的构建  Andrew算法

     for(int i = ; i < N; i++){    //先按x,y坐标排序，找到原点

         point temp;

         if(p[i].y < p[].y || ( p[i].y == p[].y && p[i].x < p[].x)){

             temp = p[i];

             p[i] = p[];

             p[] = temp;

         }

     }

     qsort(p + , N - , sizeof(p[]), cmp);  //再将除原点以外的点按极角排序

     stack[] = p[];         //先将起始的两个点压入栈内,在进行后面的判断

     stack[] = p[];

     top = ;

     for(int i = ; i < N; i++){

         while(top >=  && multi(stack[top - ], stack[top], p[i]) < )top--;         //共线的点也压入凸包内;

         top++;

         stack[top] = p[i];

     }

 }

 bool judge(){    //这个函数是关键

     for(int i=;i<top;i++){

         if((multi(stack[i-],stack[i+],stack[i]))!=&&(multi(stack[i],stack[i+],stack[i+]))!=) //判断每条边是否有至少三个点,即判断i-1,i,i+1这三个点是否在一条直线上或者i,i+1,i+2是否在一条直线上

             return false;

     }

     return true;

 }

 int main(){

     int t;

     cin>>t;

     while(t--){

         cin>>N;

         for(int i=;i<N;i++)

         scanf("%lf%lf",&p[i].x,&p[i].y);

         if(N<)puts("NO");

         else{

             Convex();

             if(judge())puts("YES");

             else puts("NO");

         }

     }

     return ;

 }