foo.cc: In function 'int main()':
foo.cc:7:6: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  if(n=4)
     ~^~
foo.cc:10:6: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  if(n=5)
     ~^~

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