/in/foo.cc: In function 'int main()':
/in/foo.cc:7:2: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(s);
  ^~~~
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:46,
                 from /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:7:8: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(s);
        ^
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:46,
                 from /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:10:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(start<strlen(s)&&start+len>=strlen(s))
     ~~~~~^~~~~~~~~~
/in/foo.cc:10:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(start<strlen(s)&&start+len>=strlen(s))
                      ~~~~~~~~~^~~~~~~~~~~
/in/foo.cc:13:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  else if(start>=strlen(s))
          ~~~~~^~~~~~~~~~~
/in/foo.cc:19:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=start+len;i<strlen(s);i++)
                       ~^~~~~~~~~~
/tmp/ccZPdgbv.o: In function `main':
foo.cc:(.text.startup+0x27): warning: the `gets' function is dangerous and should not be used.