Compilare: user.cpp: In function ‘int main()’: user.cpp:27:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[i].size();j++) ^ user.cpp:29:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[i].size();j++) ^ user.cpp:31:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=0;k<v[v[i][j]].size();k++) ^