Compilare: user.cpp: In function ‘void run()’: user.cpp:27:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(size_t it=1;it<=n;++it) ^ user.cpp: In function ‘int main()’: user.cpp:58:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(size_t i=1;i<=n;++i) ^ user.cpp:68:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(size_t i=1;i<=n;++i) ^ user.cpp:69:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(size_t j=1;j<=n;++j) ^