Compilare: user.cpp: In function ‘int main()’: user.cpp:20:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "alee.in", "r", stdin ); ^ user.cpp:21:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "alee.out", "w", stdout ); ^ user.cpp:23:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d%d", &n, &m ); ^ user.cpp:26:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d%d", &lin, &col ); ^ user.cpp:36:58: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d%d%d%d", &start.l, &start.c, &end.l, &end.c ); ^