Compilare: user.c: In function 'add': user.c:17: warning: assignment from incompatible pointer type user.c: In function 'push_back': user.c:36: warning: assignment from incompatible pointer type user.c: In function 'solve': user.c:47: warning: format '%d' expects type 'int', but argument 2 has type 'long int' user.c:50: warning: assignment from incompatible pointer type user.c:57: warning: assignment from incompatible pointer type user.c:67:2: warning: no newline at end of file