Compilare: user.c: In function ‘main’: user.c:18:3: warning: implicit declaration of function ‘abs’ [-Wimplicit-function-declaration] if ( (abs(x - Sx) + abs(y - Sy)) == S) ^ user.c:12:8: warning: unused variable ‘fout’ [-Wunused-variable] FILE *fout = freopen("cal.out", "wt", stdout); ^ user.c:11:8: warning: unused variable ‘fin’ [-Wunused-variable] FILE *fin = freopen("cal.in", "rt", stdin); ^ user.c:13:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &Sx, &Sy, &S, &N); ^ user.c:17:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^