Compilare: user.c: In function ‘main’: user.c:14:13: warning: implicit declaration of function ‘exit’ [-Wimplicit-function-declaration] exit(1); ^ user.c:14:13: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] user.c:85:17: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] exit(1); ^ user.c:5:17: warning: unused variable ‘p’ [-Wunused-variable] int n,i,j,k,p; ^ user.c:5:15: warning: unused variable ‘k’ [-Wunused-variable] int n,i,j,k,p; ^