@results= map(/^(lean : sigma)/,@arr);
print "First content=> $_\n" for @results;

##</code><code>##

foreach (@arr) {
  if (/^(lean : sigma)/) {
    print "First content=> $1\n";
  }
}

##</code><code>##

@numberlist=('First','Second','Third','Fourth','Fifth'); #and so on as high as the maximal number of matches you expect

@results= map(/^(lean : sigma)/,@arr);
$i=0;
foreach (@results) {
  print $numberlist[$i++]," content=> $_\n";
}