2.15. Exercise: Connect Four

Connect Four is a popular board game which is played by two players. In this game, players take a colored discs (red for one player, yellow for another) and drop them into a column in a suspended grid. The discs fall down until there are no available space left in the column. If any of the players form a diagonal, horizontal or vertical line with four of the players discs, player wins.

Write a program that determines for a given board state whether there is a winner or not. The game grid is always \(N\times N\), \(N \ge 4\). \(N\) is given in the first input line. In the following \(N\) lines the board configuration is given row by row, represented as strings with \(N\) elements each. The elements are ’R’ for red, ’Y’ for yellow and ’.’ for empty.

Print "yes" if there is a winner, "no" if not.

Sample I/O:

Input:
4
YRYR
RYRY
YRYR
RYRY

Output:
yes


Input:
4
RY..
YYYR
RYRY
YRRY


Output:
no