s
foo
e f
s
adflkja

##</code><code>##

use warnings;
use strict;

my $lines = "";
while (<DATA>) {
    $lines .= $_;
}

my @wanted = $lines =~ m/^(s(?:(?!e p$).)*e [^p]$)/msg;
print @wanted;

__DATA__
s
erartt
e p
s
foo
e f
s
adflkja

##</code><code>##

s
foo
e f