### CONTEXT (Previous Events):
<system_output timestamp="5516.197169"/>
<user_input timestamp="5516.507419">s</user_input>
<system_output timestamp="5516.52629">[1@s</system_output>
<user_input timestamp="5516.6301">u</user_input>
<system_output timestamp="5516.648889">[1@u</system_output>
<user_input timestamp="5516.814474">d</user_input>
<system_output timestamp="5516.835795">[1@d</system_output>
<user_input timestamp="5516.898226">o</user_input>
<system_output timestamp="5516.916738">[1@o</system_output>
<user_input timestamp="5517.019705"> </user_input>
<system_output timestamp="5517.036437">[1@ </system_output>
<user_input timestamp="5518.823582"/>
<system_output timestamp="5518.841111">chmod 755 </system_output>
<user_input timestamp="5521.557516">.</user_input>

### TARGET LINE (Extract and Classify THIS Timestamp):
<system_output timestamp="5521.558893">.</system_output>

Answer: 5521.558893, old event