Compilare: user.cpp: In function ‘int main()’: user.cpp:49:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < A[x].size(); i++) ^ user.cpp:59:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < B[x].size(); i++) ^