Compilare: user.cpp: In function ‘bool distance(std::vector<int, std::allocator<int> >)’: user.cpp:20: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘bool valid(std::vector<int, std::allocator<int> >)’: user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void normalize(std::vector<int, std::allocator<int> >&)’: user.cpp:35: warning: comparison between signed and unsigned integer expressions user.cpp:37: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void buildmat(std::vector<int, std::allocator<int> >&)’: user.cpp:60: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:125: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:126: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:127: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result