Compilare: user.cpp: In function ‘void solve()’: user.cpp:27:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("xor.in","r",stdin); ^ user.cpp:28:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("xor.out","w",stdout); ^ user.cpp:29:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&MOD); ^ user.cpp:32:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&x1,&y1,&x2,&y2); ^