Original image description on Flickr:

The large red star on the front of diesel hydraulic locomotive Mk-45-2006 of MAV, the Hungarian State railways, indicates a pre-1990 date. úttörővasút - Pioneers Railway, Buda Hills, Budapest, constructed 1948-1950.

6 of these locomotives were contructed by the 23rd August factory in Bucharest Romania, to a gauge of 760mm. . They entered service in 1973. A conspectus of activity here in the 21st century can be seen here In 1994, a further 4, nos 2007-10 which had been in service in Eastern Hungary, were transferred to the children's railway here for spare parts only. More about the system here.