Compilare: user.cpp: In function ‘int main()’: user.cpp:137: warning: comparison between signed and unsigned integer expressions user.cpp:174: warning: comparison between signed and unsigned integer expressions user.cpp:178: warning: comparison between signed and unsigned integer expressions user.cpp:188: warning: comparison between signed and unsigned integer expressions user.cpp:74: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:75: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:77: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:80: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result