/in/foo.c: In function 'main':
/in/foo.c:5:5: warning: 'gets' is deprecated [-Wdeprecated-declarations]
     gets(s);
     ^~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:7:10: warning: iteration 100 invokes undefined behavior [-Waggressive-loop-optimizations]
      if(s[i]=='O')tj++;
         ~^~~
/in/foo.c:6:5: note: within this loop
     for(int i=0;i<=100;i++){
     ^~~
/tmp/ccOe2pBg.o: In function `main':
foo.c:(.text.startup+0xc): warning: the `gets' function is dangerous and should not be used.