/in/foo.c: In function 'main':
/in/foo.c:5:10: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'int' [-Wformat=]
  scanf("%s",a);
          ^
/in/foo.c:6:11: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'int' [-Wformat=]
  printf("%s",a);
           ^
/in/foo.c:5:2: warning: 'a' is used uninitialized in this function [-Wuninitialized]
  scanf("%s",a);
  ^~~~~~~~~~~~~