YY's new problem

Given a permutation P of 1 to N, YY wants to know whether there exists such three elements P[i₁], P[i₂], P[i₃] that
P[i₁]-P[i₂]=P[i₂]-P[i₃], 1<=i₁<i₂<i₃<=N.

The first line is T(T<=60), representing the total test cases.
Each test case comes two lines, the former one is N, 3<=N<=10000, the latter is a permutation of 1 to N.

For each test case, just output 'Y' if such i₁, i₂, i₃ can be found, else 'N'.

2
3
1 3 2
4
3 2 4 1

N
Y

2011 Multi-University Training Contest 1 - Host by HNU