$i-$l+1

##</code><code>##

# Start of match in first string
# End of match in first string
[ $i-$l+1, $i+1 ]

##</code><code>##

# Start of match in first string
# End of match in first string
# Start of match in second string
# End of match in second string
[ $i-$l+1, $i+1, $j-$l+1, $j+1 ]

##</code><code>##

# Start of match in first string
# Start of match in second string
# Length of match
[ $i-$l+1, $j-$l+1, $l ]

##</code><code>##

map { substr($s, $_, $best_l) }