Compilare: user.c: In function ‘main’: user.c:16:3: warning: implicit declaration of function ‘exit’ [-Wimplicit-function-declaration] exit(1); ^~~~ user.c:16:3: warning: incompatible implicit declaration of built-in function ‘exit’ user.c:16:3: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’ user.c:23:3: warning: incompatible implicit declaration of built-in function ‘exit’ exit(1); ^~~~ user.c:23:3: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’ user.c:26:2: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(ip, "%d", &n); ^~~~~~~~~~~~~~~~~~~~ user.c:30:3: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(ip, "%lld", &a[i]); ^~~~~~~~~~~~~~~~~~~~~~~~~