Compilare: user.cpp: In function ‘int main(int, const char**)’: user.cpp:20:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(size_t i = 0; i < n; ++i) { ^ user.cpp:35:7: warning: variable ‘startXIdx’ set but not used [-Wunused-but-set-variable] int startXIdx = 0; ^ user.cpp:46:7: warning: variable ‘startYIdx’ set but not used [-Wunused-but-set-variable] int startYIdx = 0; ^