Compilare: user.cpp: In function ‘int main()’: user.cpp:68:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (is=0;is<vs[ivs].size();is++) ^ user.cpp:89:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (is=1;is<vs[0].size();is++) ^ user.cpp:97:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (is=0;is<vs[1].size();is++) ^