Compilare: user.cpp: In function ‘int check(int)’: user.cpp:19: warning: comparison between signed and unsigned integer expressions user.cpp:22: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: 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 ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:82: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:87: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result