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    from re import sub
    
    
    n, m = map(int, input().split())
    
    matrix = [""] * m
    line = ""
    pattern = r"[a-zA-Z0-9][^a-zA-Z0-9]+[a-zA-Z0-9]"
    
    for _ in range(n):
        line = input()
        for i in range(m):
            matrix[i] += line[i]
    
    def replace(match):
        return f"{match.group(0)[0]} {match.group(0)[-1]}"
    
    print(sub(pattern, replace, "".join(matrix)))