open(IN,"check_max_tdiff.log");
while(<IN>){
    if($_=~/(F\S+)\s+(\S+)/){
	$frf=$1;
	$maxtdiff=$2;
	if($maxtdiff==0.0||abs($maxtdiff)>1500){
	    printf("%s  %s\n",$frf,$maxtdiff);
	}
    }
}