Compilare: user.cpp: In function ‘int main()’: user.cpp:33:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( IN , "r" , stdin ); ^ user.cpp:34:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( OUT , "w" , stdout ); ^ user.cpp:35:53: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d %d %d %d" , &n , &m , &start , &fin ); ^ user.cpp:38:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d%d" , &x, &y ); ^ user.cpp:44:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&w); ^ user.cpp:56:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( IN , "r" , stdin ); ^ user.cpp:57:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d" ,&fin ); ^ user.cpp:58:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d" ,&fin ); ^ user.cpp:59:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d" ,&fin ); ^ user.cpp:60:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d" ,&fin ); ^ user.cpp:63:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf( "%d%d" , &x, &y ); ^