Compilare: user.cpp: In function ‘int main()’: user.cpp:30:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.in","r",stdin); ^ user.cpp:31:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.out","w",stdout); ^ user.cpp:33:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &N); ^ user.cpp:37:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &val); ^ user.cpp:43:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &Q); ^ user.cpp:47:47: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d\n", &i, &j, &x, &y); ^