Compilare: user.cpp: In function ‘void scan()’: user.cpp:62: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:63: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:65: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:68: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void solve()’: user.cpp:114: warning: suggest parentheses around ‘-’ inside ‘<<’ user.cpp:124: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result