Compilare: user.cpp: In function ‘void Add(std::vector<char, std::allocator<char> >&, std::vector<char, std::allocator<char> >&)’: user.cpp:21: warning: comparison between signed and unsigned integer expressions user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result