foo.c:2:1: warning: return type defaults to 'int' [-Wimplicit-int]
    2 | Output(int a[], int n)
      | ^~~~~~
foo.c: In function 'F':
foo.c:33:12: warning: unused variable 'j' [-Wunused-variable]
   33 |     int i, j;
      |            ^
foo.c: In function 'Output':
foo.c:9:1: warning: control reaches end of non-void function [-Wreturn-type]
    9 | }
      | ^

[Hydro](https://hydro.ac)提供评测服务