Simple task: Rotate photos in 1000 member listings

Our client has a website where members upload photos of their house for doing home exchanges for holidays. Some members have uploaded images that need to be rotated. When the members uploaded their photos, the rotate image feature was not available. Approximately 5% of the photos need to be rotated. To rotate an image you just need to click on a button in the back-office web tool when you go through the list of photos. Listings have a variable number of photos, from 5 to 40, most likely 15 photos. My estimate is that it takes on average 20 seconds per listing. So, for 1000 listings it should take around 5.5 hours. There are around 5000 listings in total, we are dividing the job into 5 blocks of 1000 member listings each, to assign the job to 5 freelancers. So the task is just to quickly go through the images in the listing to find those that need to be rotated and click a button to do it. No technical skills required, just the discipline to do this boring job.