Compilare: user.cpp: In function ‘bool bfs(int)’: user.cpp:38:10: warning: unused variable ‘j’ [-Wunused-variable] int i , j ; ^ user.cpp: In function ‘void input()’: user.cpp:76:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%d" , &n ) ; ^ user.cpp:79:72: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%d%d%d%d" , &a[ i ].x , &a[ i ].y , &a[ i ].z , &a[ i ].t ) ; ^ user.cpp: In function ‘int main()’: user.cpp:126:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ( "canibali.in" , "r" , stdin ) ; ^ user.cpp:127:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ( "canibali.out" , "w" , stdout ) ; ^