put this code in your DOCUMENT_ROOT/.htaccess
file:
RewriteEngine On
# remove /example/ from URLs
RewriteCond %{THE_REQUEST} /example/ [NC]
RewriteRule ^example/(.*)$ /$1 [L,R=301,NC,NE]
# add www to host name
RewriteCond %{HTTP_HOST} ^domain\.com$ [NC]
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]
# other than /js/ internally prefix /example/ before all URIs
RewriteCond $1 !js [NC]
RewriteRule ^((?!example/)[a-z]{2}/.*)$ /example/$1 [L,NC]
# if a matching .php file is found add .php internally
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{DOCUMENT_ROOT}/$1.php -f
RewriteRule ^([^.]+)/?$ $1.php [L]