foo.c: In function 'main':
foo.c:30:17: warning: unused variable 'm' [-Wunused-variable]
   30 |         int n,z,m,i;
      |                 ^
foo.c:30:15: warning: unused variable 'z' [-Wunused-variable]
   30 |         int n,z,m,i;
      |               ^
foo.c: In function 'S':
foo.c:14:1: warning: control reaches end of non-void function [-Wreturn-type]
   14 | }
      | ^

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