foo.cc:5:15: error: stray '\' in program
  scanf("%d",&n\n);
               ^
foo.cc: In function 'int main()':
foo.cc:5:16: error: expected ')' before 'n'
  scanf("%d",&n\n);
                ^

自豪的采用jd5进行评测(github.com/masnn/jd5)