foo.cc:54:1: warning: "/*" within comment [-Wcomment]
 /* if(x)
  
foo.cc: In function 'void dp(int)':
foo.cc:7:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<son[x].size();i++)
              ~^~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:29:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&m,&n);
  ~~~~~^~~~~~~~~~~~~~
foo.cc:33:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d%d",&x,&a[i]);
    ~~~~~^~~~~~~~~~~~~~~~~

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