q=int(input());A=[]
for i in range(q):
    n=int(input())
    X=[];Y=[]
    for j in range(n):
        x,y = map(int, input().split())
        X.append(x);Y.append(y);
    xmin=min(X);xmax=max(X)
    ymin=min(Y);ymax=max(Y)
    for i in range(n):
        if (X[i]==xmin or X[i]==xmax) or (Y[i]==ymin or Y[i]==ymax) :
            ans='YES'
        else:
            ans='NO'
            break
    A.append(ans)                
for i in A:
    print(i)