Hi sanku,

I think that this code does what you need:

$a=<>;
while ($a=~s/(\s?)(\w{10})(\w)/$1$2 $3/){}
$a=~s/((\w+\s){5})/$1\n/g;
print $a,"\n";
[download]

The code assumes that the original string comes from STDIN and the final strings goes to STDOUT. I presume you'll have no problem adapting it to your real needs.