/in/foo.cc: In function 'int main()':
/in/foo.cc:14:2: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(s);
  ^~~~
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /usr/include/c++/6/ext/string_conversions.h:43,
                 from /usr/include/c++/6/bits/basic_string.h:5417,
                 from /usr/include/c++/6/string:52,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 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:14:8: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(s);
        ^
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /usr/include/c++/6/ext/string_conversions.h:43,
                 from /usr/include/c++/6/bits/basic_string.h:5417,
                 from /usr/include/c++/6/string:52,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 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:31:23: warning: format '%f' expects argument of type 'double', but argument 2 has type 'int' [-Wformat=]
  printf("%.2f",sum,avg);
                       ^
/in/foo.cc:31:23: warning: too many arguments for format [-Wformat-extra-args]
/in/foo.cc:30:11: warning: 'sum' may be used uninitialized in this function [-Wmaybe-uninitialized]
  avg = sum/(N*N);
        ~~~^~~~~~
/tmp/cceLMm1E.o: In function `main':
foo.cc:(.text.startup+0xe): warning: the `gets' function is dangerous and should not be used.