2^N participants (P₁ , P₂ , P₃ .... , P_2^N ) have enrolled for a knockout chess tournament. In the first round, each participant P_2k-1 is to play against participant P_2k, (1 ≤ k ≤ 2^N-1) . Here is an example for k = 4 :

Some information about all the participants is known in the form of a triangular matrix A with dimensions
(2^N-1) X (2^N-1). If A_ij = 1 (i > j), participant P_i is a better player than participant P_j, otherwise A_ij = 0 and participant P_j is a better player than participant P_i. Given that the better player always wins, who will be the winner of the tournament?

Note : Being a better player is not transitive i.e if P_i is a better player than P_j and P_j is a better player than P_k, it is not necessary that P_i is a better player than P_k .

Input

The first line consists of N. Then, 2^N-1 lines follow, the i^th line consisting of i space separated integers A_{i+1 1} , A_{i+1 2} , .... A_{i+1 i}

Output

A single integer denoting the id of the winner of the tournament.

Constraints

1 ≤ N ≤ 10
A_ij = {0, 1} (i > j)