/in/foo.cc: In function 'int count(int)':
/in/foo.cc:55:17: warning: suggest parentheses around comparison in operand of '&' [-Wparentheses]
  if(tree[2 * x] == 0 & tree[2 * x + 1] == 0) return 1;
     ~~~~~~~~~~~~^~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:72:2: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(s2+1);
  ^~~~
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:72:11: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(s2+1);
           ^
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:73:2: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(s1+1);
  ^~~~
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:73:11: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(s1+1);
           ^
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: In function 'int find(int)':
/in/foo.cc:18:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/tmp/ccLqd6vY.o: In function `main':
foo.cc:(.text.startup+0x9): warning: the `gets' function is dangerous and should not be used.