perl -Fhello -0777 -lane 'print $#F' /tmp/hh

# shorter:
perl -apFhello -0777e '$_=$#F'  < /tmp/hh

# with check for word boundry (e.g. to exclude "Othello" or mispelled "cello")
perl -apF'\bhello\b' -0777e '$_=$#F'  < /tmp/hh