foo.cc:20:1: warning: "/*" within comment [-Wcomment]
   20 | /*
      |  
foo.cc: In function 'int main()':
foo.cc:637:20: warning: unused variable 'c' [-Wunused-variable]
  637 |  int i,j,k,m,n,a,b,c;
      |                    ^

[Hydro](https://hydro.ac)提供评测服务