channel II

Example

Input

7 4 DEFG FEDA EFGB BGEA AGFD DABC CADE

Output

ABCDEFG

inputFormat

Input

7 4 DEFG FEDA EFGB BGEA AGFD DABC CADE

outputFormat

Output

ABCDEFG

样例

7 4
DEFG
FEDA
EFGB
BGEA
AGFD
DABC
CADE

ABCDEFG