Compilare: user.cpp: In function ‘void sum()’: user.cpp:34: warning: unused variable ‘j’ user.cpp:34: warning: unused variable ‘k’ user.cpp: In function ‘int main()’: user.cpp:128: warning: comparison between signed and unsigned integer expressions user.cpp:124: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result 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 ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result