Compilare: user.cpp: In function ‘void solve()’: user.cpp:48:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<a[x].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:76:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<a[i].size();j++) ^