foo.c: In function 'main':
foo.c:7:16: warning: zero-length gnu_printf format string [-Wformat-zero-length]
    7 |         printf("");
      |                ^~
foo.c:9:16: warning: zero-length gnu_printf format string [-Wformat-zero-length]
    9 |         printf("");
      |                ^~
foo.c:6:13: warning: unused variable 'arr' [-Wunused-variable]
    6 |         int arr[12] = { 31,28,31,30,31,30,31,31,30,31,30,31 };
      |             ^~~

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