$\left[\begin{array}{ccccc}& 1918\mathrm{.}5& 2013\mathrm{.}8& 2068\mathrm{.}5& 433\mathrm{.}2\\ 2068\mathrm{.}7& & 1711\mathrm{.}6& 485\mathrm{.}2& 1961\mathrm{.}2\\ 1884\mathrm{.}4& 1914\mathrm{.}7& & 2035\mathrm{.}6& 2186\mathrm{.}3\\ 505\mathrm{.}9& 2243\mathrm{.}6& 1997\mathrm{.}7& & 2163\mathrm{.}7\\ & & & & \end{array}\right]$

You inadvertently smudged the ink on the last line and can't

read it anymore, but you've just intercepted a new ciphertext

that you know was encrypted using the same key as the last

one. The new ciphertext reads ACMHSDOOFOYMEQE. What is

the plaintext?