/in/foo.cc: In function 'int main()':
/in/foo.cc:8:9: error: expected initializer before 'double'
    8 |         double d;
      |         ^~~~~~
/in/foo.cc:9:20: error: 'c' was not declared in this scope
    9 |         cin>>a>>b>>c>>d;
      |                    ^
/in/foo.cc:9:23: error: 'd' was not declared in this scope
    9 |         cin>>a>>b>>c>>d;
      |                       ^