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### check file ###
if(length($evt) == 0){
    opendir(dir,"$data_dir");
    @files = grep(/x${sensor}/ && /.evt$/, readdir(dir));
    $evt = $files[0];
    print "Search $data_dir\n";
    print "Found $evt\n";
    if($check==1){
	print "OK? [n -> EXIT]: ";
	$yn = <STDIN>;
	chomp $yn;
	if("$yn" eq "n"){
	    print "EXIT\n";
	    exit;
	}else{
	    print "Make weighted bgd spectrum file.\n";
	}
    }
}
###
if (!-e "${data_dir}/${evt}") {
    print "cannot find ${data_dir}/${evt}\n";
    print "exit\n";
    exit;
}else{
    print "found ${data_dir}/${evt}\n";
}
if (!-e "${ehk_dir}/${ehk_file}") {
    print "cannot find ${ehk_dir}/${ehk_file}\n";
    print "exit\n";
    exit;
}else{
    print "found ${ehk_dir}/${ehk_file}\n";
}
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