B'Fox Ciel is playing a mobile puzzle game called "Two Dots". The basic levels are played on a board of size n xe2 x80 x89 xc3 x97 xe2 x80 x89m cells, like this: Each cell contains a dot that has some color. We will use different uppercase Latin characters to express different colors. The key of this game is to find a cycle that contain dots of same color. Consider 4 blue dots on the picture forming a circle as an example. Formally, we call a sequence of dots d1, xe2 x80 x89d2, xe2 x80 x89..., xe2 x80 x89dk a cycle if and only if it meets the following condition: Determine if there exists a cycle on the field. The first line contains two integers n and m (2 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n, xe2 x80 x89m xe2 x80 x89 xe2 x89 xa4 xe2 x80 x8950): the number of rows and columns of the board. Then n lines follow, each line contains a string consisting of m characters, expressing colors of dots in each line. Each character is an uppercase Latin letter. Output "Yes" if there exists a cycle, and "No" otherwise. In first sample test all 'A ' form a cycle. In second sample there is no such cycle. The third sample is displayed on the picture above ( 'Y ' = Yellow, 'B ' = Blue, 'R ' = Red).'...