foo.c: In function 'main':
foo.c:6:9: warning: 'gets' is deprecated [-Wdeprecated-declarations]
    6 |         gets(ch);
      |         ^~~~
In file included from foo.c:1:
/nix/store/y8wfrgk7br5rfz4221lfb9v8w3n0cnyd-glibc-2.37-8-dev/include/stdio.h:605:14: note: declared here
  605 | extern char *gets (char *__s) __wur __attribute_deprecated__;
      |              ^~~~
foo.c:13:23: warning: 'a' may be used uninitialized [-Wmaybe-uninitialized]
   13 |         for (int i = a[0] - 1; i >= 0; i--)
      |                      ~^~~
foo.c:8:13: note: 'a' declared here
    8 |         int a[100000],j=0;//储存空格的位置
      |             ^
/nix/store/74y3751gsixaz9797ib0hp7c658sp1y5-binutils-2.40/bin/ld: /tmp/ccSFlI0P.o: in function `main':
foo.c:(.text.startup+0x13): warning: the `gets' function is dangerous and should not be used.

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