Compilare: user.cpp: In function ‘int main()’: user.cpp:21:11: warning: variable ‘in’ set but not used [-Wunused-but-set-variable] FILE *in, *out; ^~ user.cpp:25:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:34:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^