/in/foo.c: In function 'Max':
/in/foo.c:7:4: warning: array subscript has type 'char' [-Wchar-subscripts]
   a[s[i]]++;
    ^
/in/foo.c: In function 'Min':
/in/foo.c:17:4: warning: array subscript has type 'char' [-Wchar-subscripts]
   a[s[i]]++;
    ^
/in/foo.c:15:27: warning: unused variable 'min' [-Wunused-variable]
  int a[200]={ 0 },k=200,i,min=0;
                           ^~~
/in/foo.c: In function 'main':
/in/foo.c:26:2: 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__;
              ^~~~
/tmp/ccPWTHTK.o: In function `main':
foo.c:(.text.startup+0xf): warning: the `gets' function is dangerous and should not be used.