foo.c: In function 'main':
foo.c:31:20: warning: unused variable 'c' [-Wunused-variable]
   31 |         int a[200],c[200];
      |                    ^
foo.c:30:13: warning: unused variable 'n' [-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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