/in/foo.cc: In function 'void Match(std::__cxx11::string&)':
/in/foo.cc:9:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<s.length(); i++)
                  ~^~~~~~~~~~~
/in/foo.cc:16:11: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
         if(s[i]==')') 
           ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:49:5: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(s1);
     ^~~~
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:49:12: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
     gets(s1);
            ^
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__;
              ^~~~
/tmp/ccZOCkJx.o: In function `main':
foo.cc:(.text.startup+0x1c): warning: the `gets' function is dangerous and should not be used.