Compilare: user.cpp: In function ‘void add(std::vector<int>&, std::vector<int>)’: user.cpp:15:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(t=i=0; i<max(b.size(),a.size()) || t; ++i) { ^ user.cpp:16:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i==a.size()) a.push_back(0); ^ user.cpp:17:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] a[i]+=(i<b.size()?b[i]:0)+t; ^ user.cpp: In function ‘std::vector<int> mul(std::vector<int>, int)’: user.cpp:28:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<a.size() || t; ++i) { ^ user.cpp:29:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] int cif=(i<a.size()?a[i]:0)*x+t; ^