Main.cc:11:15: error: ‘long long int free’ redeclared as different kind of entity
   11 | long long n,m,free;
      |               ^~~~
In file included from /usr/include/c++/9/cstdlib:75,
                 from /usr/include/c++/9/ext/string_conversions.h:41,
                 from /usr/include/c++/9/bits/basic_string.h:6493,
                 from /usr/include/c++/9/string:55,
                 from /usr/include/c++/9/bits/locale_classes.h:40,
                 from /usr/include/c++/9/bits/ios_base.h:41,
                 from /usr/include/c++/9/ios:42,
                 from /usr/include/c++/9/ostream:38,
                 from /usr/include/c++/9/iostream:39,
                 from Main.cc:3:
/usr/include/stdlib.h:565:13: note: previous declaration ‘void free(void*)’
  565 | extern void free (void *__ptr) __THROW;
      |             ^~~~
Main.cc: In function ‘int main()’:
Main.cc:37:14: error: assignment of function ‘void free(void*)’
   37 |         free = n-m;
      |         ~~~~~^~~~~
Main.cc:42:23: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
   42 |         else if(free==1){
      |                       ^