/in/foo.c:5:1: error: unknown type name 'bool'
 bool Isword(char a);
 ^~~~
/in/foo.c: In function 'main':
/in/foo.c:12:2: 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__;
              ^~~~
/in/foo.c:10:34: warning: unused variable 't' [-Wunused-variable]
  int i,j ,c[40000]={0},count=0,k,t=0;
                                  ^
/in/foo.c: At top level:
/in/foo.c:46:1: error: unknown type name 'bool'
 bool Isword(char a)
 ^~~~
/in/foo.c: In function 'Isword':
/in/foo.c:51:11: error: 'false' undeclared (first use in this function)
    return false;
           ^~~~~
/in/foo.c:51:11: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:52:9: error: 'true' undeclared (first use in this function)
  return true;
         ^~~~
/in/foo.c:53:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^