foo.cc: In function 'int foundt(int)':
foo.cc:21:9: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  while(x=addundis(x)){
        ~^~~~~~~~~~~~
foo.cc: In function 'int addundis(int)':
foo.cc:36:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。