Guitar has six major chords A, B, C, D, E and F

Suppose it takes 1 sec to play one chord.

A sweet melody is defined by a regular expression pattern (for eg E*(F|A) + B)

A band wants to play a melody for X seconds. What is the minimun margin of error(in terms of the number of seconds) the band can

encounter.

X < 500

melody pattern length < 30