gcc versions later are not supported

I just set up a Ubuntu.I'm trying to turn the yolo of darknet. and I've got this error.

/usr/local/cuda/include/crt/host_config.h:138:2: error: #error -- unsupported GNU version! gcc versions later than 8 are not supported!  138 | #error -- unsupported GNU version! gcc versions later than 8 are not supported!

Even I tried

sudo apt install gcc-4.9 g++-4.9

I got

Package g++-4.9 is not available, but is referred to by another package.This may mean that the package is missing, has been obsoleted, oris only available from another sourceE: Package 'gcc-4.9' has no installation candidateE: Package 'g++-4.9' has no installation candidate

It seems that the version error occurs by downloading the recent version.Do you know how to downgrade the gcc version?