Compilare: user.cpp: In function ‘int main()’: user.cpp:14:9: warning: unused variable ‘f’ [-Wunused-variable] FILE *f = freopen("alee.in", "r",stdin); ^ user.cpp:15:9: warning: unused variable ‘g’ [-Wunused-variable] FILE *g = freopen("alee.out", "w",stdout); ^ user.cpp:21:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:23:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &l, &c); ^ user.cpp:27:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &L1, &C1); ^ user.cpp:28:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &L2, &C2); ^