/in/foo.cc:8:1: error: expected initializer before 'float'
    8 | float r1,r2,R;
      | ^~~~~
/in/foo.cc:9:6: error: expected constructor, destructor, or type conversion before '(' token
    9 | scanf("%f%f",&r1,&r2);
      |      ^
/in/foo.cc:10:1: error: 'R' does not name a type
   10 | R=1/(1/r1+1/r2);
      | ^
/in/foo.cc:11:7: error: expected constructor, destructor, or type conversion before '(' token
   11 | printf("%.2f\n",R);
      |       ^
/in/foo.cc:12:1: error: expected unqualified-id before 'return'
   12 | return 0;
      | ^~~~~~