Compilare: user.cpp: In function ‘int main()’: user.cpp:12:54: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] #define openfile {freopen("harbingers.in","rt",stdin);freopen("harbingers.out","wt",stdout);} ^ user.cpp:59:12: note: in expansion of macro ‘openfile’ if (HOME) openfile; ^ user.cpp:12:92: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] #define openfile {freopen("harbingers.in","rt",stdin);freopen("harbingers.out","wt",stdout);} ^ user.cpp:59:12: note: in expansion of macro ‘openfile’ if (HOME) openfile; ^ user.cpp:60:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:63:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &u, &v, &w); ^ user.cpp:66:48: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] FOR(i, 2, n) scanf("%lld%lld", &s[i], &val[i]); ^