#!/usr/bin/perl

# http://perlmonks.org/?node_id=1192942

use strict;
use warnings;

while(<DATA>)
  {
  print /(.*)/, " -> ", /\d/
    ? s/(\D)(\d+)/$1 x ($2 + 1)/ger
    : s/(\D)\K(\1+)/ length $2 /ger;
  }

__DATA__
raaaammmmmaaaaaj
ra3m4a4j
foobar really?