foo.cc: In function 'int count_7(int)':
foo.cc:9:8: warning: unused variable 'b' [-Wunused-variable]
  int a,b;
        ^
foo.cc: In function 'int main()':
foo.cc:26:8: warning: statement has no effect [-Wunused-value]
  for (q;q<=w;q++)
        ^

[Hydro](https://hydro.ac)提供评测服务