Compilare: user.cpp: In function ‘void add(int)’: user.cpp:37:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();++i) if(!D[id][v[x][i]]) ^ user.cpp: In function ‘int main()’: user.cpp:111:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<sol[i].size();++j) g<<sol[i][j]<<" "; ^ user.cpp:83:9: warning: ‘j’ may be used uninitialized in this function [-Wmaybe-uninitialized] int j; ^