Compilare: user.cpp: In function ‘std::string s(std::string, std::string)’: user.cpp:16: warning: comparison between signed and unsigned integer expressions user.cpp:16: warning: comparison between signed and unsigned integer expressions user.cpp:25: warning: comparison between signed and unsigned integer expressions user.cpp:34: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:79: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:80: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:81: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result