print " Enter the number of student that you want to add\n";
my $std = <STDIN>;
chomp $std;

open(FILE, "$stdInfo") || die "couldn't open $stdInfo for reading";
my @in=<FILE>;
close(FILE);

open (FILE, ">$stdInfo") ||die "couldn't open $stdInfo for writing";

for (@in)
{
        print FILE unless ( $_ =~ /^\Q$std\E\b/ );
        print $std;
}
close(FILE);