Compilare: user.cpp: In function ‘void solve(int)’: user.cpp:16:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[x].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:38:5: warning: ‘ok’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(ok){g<<s1<<'\n'; ^