foo.cc: In function 'int e(long int*, long int)':
foo.cc:11:2: error: invalid operands of types 'long int*' and 'long int' to binary 'operator/'
 a/=p;
 ~^~~
foo.cc:11:4: error:   in evaluation of 'operator/=(long int*, long int)'
 a/=p;
    ^
foo.cc: At global scope:
foo.cc:33:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main()
      ^

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