#! /usr/bin/perl

$test = 'aaEa2.a';
$test =~ /^([^E]*?)E([^E]+?)\.[^E]*?$/? print "yes\n": print "no\n";
$test2 = 'aaa2E.a';
$test2 =~ /^([^E]*?)E([^E]+?)\.[^E]*?$/? print "yes\n": print "no\n";
$test3 = 'aEaEa2.a';
$test3 =~ /^([^E]*?)E([^E]+?)\.[^E]*?$/? print "yes\n": print "no\n";

_ _END_ _

yes
no
no