foo.c: In function 'main':
foo.c:8:23: warning: implicit declaration of function 'squrt' [-Wimplicit-function-declaration]
    8 |                 int n=squrt(x);
      |                       ^~~~~
foo.c:15:20: error: 'x1' undeclared (first use in this function); did you mean 'x'?
   15 |                 if(x1>n)
      |                    ^~
      |                    x
foo.c:15:20: note: each undeclared identifier is reported only once for each function it appears in
foo.c:15:23: error: 'n' undeclared (first use in this function)
   15 |                 if(x1>n)
      |                       ^

[Hydro](https://hydro.ac)提供评测服务