/in/foo.c: In function 'main':
/in/foo.c:22:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s1);
  ^~~~
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:23:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s2);
  ^~~~
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:18:14: warning: unused variable 'ns' [-Wunused-variable]
  int i,n1,n2,ns;
              ^~
/in/foo.c:18:11: warning: unused variable 'n2' [-Wunused-variable]
  int i,n1,n2,ns;
           ^~
/in/foo.c:18:8: warning: unused variable 'n1' [-Wunused-variable]
  int i,n1,n2,ns;
        ^~
/in/foo.c:18:6: warning: unused variable 'i' [-Wunused-variable]
  int i,n1,n2,ns;
      ^
/tmp/ccGjjqMw.o: In function `main':
foo.c:(.text.startup+0x1d): warning: the `gets' function is dangerous and should not be used.