foo.cc: In function 'int main()':
foo.cc:11:8: error: 'x1' was not declared in this scope; did you mean 'x'?
   11 |  while(x1<x)
      |        ^~
      |        x
foo.cc:10:6: warning: unused variable 'i' [-Wunused-variable]
   10 |  int i=2;
      |      ^

[Hydro](https://hydro.ac)提供评测服务