/in/foo.cc: In function 'int main()':
/in/foo.cc:40:24: error: 'ans' was not declared in this scope
         if(check(mid)) ans=mid,r=mid-esp;
                        ^~~
/in/foo.cc:43:22: error: 'ans' was not declared in this scope
     printf("%.2lf\n",ans);
                      ^~~