foo.cc: In function 'int main()':
foo.cc:54:24: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<n<<"="<<x<<"+"<<y<<endl;
                        ^
foo.cc:54:19: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<n<<"="<<x<<"+"<<y<<endl;
                   ^~~

[Hydro](https://hydro.ac)提供评测服务