foo.cc: In function 'int main()':
foo.cc:8:2: error: expected ',' or ';' before 'int'
    8 |  int a=m%1000/100;
      |  ^~~
foo.cc:11:26: error: 'a' was not declared in this scope
   11 |  int n=d*1000+c*100+b*10+a;
      |                          ^

[Hydro](https://hydro.ac)提供评测服务