/in/foo.cc: In function 'int main()':
/in/foo.cc:4:6: warning: unused variable 'a' [-Wunused-variable]
    4 |  int a,b;
      |      ^
/in/foo.cc:4:8: warning: unused variable 'b' [-Wunused-variable]
    4 |  int a,b;
      |        ^