/in/foo.c: In function 'compute':
/in/foo.c:105:17: warning: 'gets' is deprecated [-Wdeprecated-declarations]
                 gets(buf);
                 ^~~~
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:120:24: warning: array subscript has type 'char' [-Wchar-subscripts]
                 instack[stack[top]] = 0;
                        ^
/in/foo.c:121:17: warning: 'gets' is deprecated [-Wdeprecated-declarations]
                 gets(buf);
                 ^~~~
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:143:24: warning: array subscript has type 'char' [-Wchar-subscripts]
                 instack[stack[top]] = 0;
                        ^
/in/foo.c:147:28: warning: array subscript has type 'char' [-Wchar-subscripts]
                     instack[stack[top]] = 0;
                            ^
/in/foo.c:152:13: warning: 'gets' is deprecated [-Wdeprecated-declarations]
             gets(buf);
             ^~~~
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__;
              ^~~~
/tmp/ccwUigxj.o: In function `compute':
foo.c:(.text+0x1f6): warning: the `gets' function is dangerous and should not be used.