Multiply all negative values of DEM by -1 in QGIS Raster Calculator

I have a Digital Elevation Model raster with negative values in QGIS software. I would like to know how to multiply all negative values by -1, i.e., all values less than 0, turning them into positive values.

I tried this:

("DEM" < 0 ) * -1

I have two DEMs, one is from the base of SRTM and the other is Sentinel 1. In DEM Sentinel I have negative values and in SRTM positive values. In my view, negative values should only appear in ocean bathymetry data. To delineate high-resolution watersheds and drainage patterns, I need to have the values well adjusted.