i have a question about size

[fabio gabbianelli]

hi, i want to write a piano accompaniment. i write 2 scores,  melody and the 
piano score but i want the melody's size smaller....i have searched in the 
manual but i didn't find it
i have set the lyl file so:

\header {...
}

melody = {...
}

upper = \relative c'' {...
}

lower = \relative c {...
}

\score {
  <<
    \new Voice = "mel" { \autoBeamOff \melody }
    \new PianoStaff <<
      \new Staff = "upper" \upper
      \new Staff = "lower" \lower
    >>
  >>

}

thanx!
fabio

 ps: i didin't write the notes, i write just the file's structure