foo.cc: In function 'int main()':
foo.cc:4:8: warning: unused variable 'b' [-Wunused-variable]
    4 |  int a,b,c,d,e;
      |        ^
foo.cc:4:10: warning: unused variable 'c' [-Wunused-variable]
    4 |  int a,b,c,d,e;
      |          ^
foo.cc:4:12: warning: unused variable 'd' [-Wunused-variable]
    4 |  int a,b,c,d,e;
      |            ^
foo.cc:4:14: warning: unused variable 'e' [-Wunused-variable]
    4 |  int a,b,c,d,e;
      |              ^

[Hydro](https://hydro.ac)提供评测服务