Compilare: user.cpp: In function ‘int main()’: user.cpp:42:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(size_t i = 0; i < N1; i ++) ^ user.cpp:57:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(size_t i = 0; i < N1; i ++) ^ user.cpp:65:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(size_t i = N1; i < N2; i ++) ^