#include<bits/stdc++.h>
using namespace std;
main()
{
int a,b,k,p,t;
scanf("%d",&t);
int val[t][100],lad[t];
for(a=0;a<t;a++)
{
scanf("%d",&lad[a]);
for(b=0;b<lad[a];b++)
scanf("%d%d",&val[a][b]);
}
for(a=0;a<t;a++)
{
int check=0;
k=lad[a]%2;
if(val[a][0]==1&&val[a][lad[a]-1]==1&&k==1)
{
k=(lad[a]/2);
p=0;
for(b=1;b<=k;b++)
{
int a=val[a][b]-val[a][p];
if(a==1)
{
p++;
}
else
{
check=1;
break;
}
}
if(check==0)
{
p=k+1;
for(b=k;b<lad[a]-1;b++)
{
int a=val[a][b]-val[a][p];
if(a==1)
p++;
else
{
check=1;
break;
}
}
}
}
else
{
check=1;
}
if(check==0)
printf("\nyes");
else
printf("\nno");
}
}
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