Compilare: user.cpp: In function ‘int main()’: user.cpp:83:9: warning: unused variable ‘i2’ [-Wunused-variable] int i2 = i + 1; ^ user.cpp:84:9: warning: unused variable ‘j2’ [-Wunused-variable] int j2 = j - 1; ^ user.cpp:49:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("harrypotter.in", "r", stdin); ^ user.cpp:50:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("harrypotter.out", "w", stdout); ^