foo.cc: In function 'int main()':
foo.cc:8:11: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(a);
           ^
In file included from /usr/include/stdio.h:862:0,
                 from /usr/include/c++/7/cstdio:42,
                 from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:46,
                 from foo.cc:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:232:1: note: declared here
 gets (char *__str)
 ^~~~
foo.cc:11:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(i=0; i<strlen(a);i++)
              ~^~~~~~~~~~
foo.cc:17:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0; i<strlen(a);i++)
           ~^~~~~~~~~~
foo.cc:8:9: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result [-Wunused-result]
     gets(a);
     ~~~~^~~
/tmp/ccg4uAr3.o: In function `main':
foo.cc:(.text.startup+0x43): warning: the `gets' function is dangerous and should not be used.

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