Compilare: user.cpp: In function ‘void prefix()’: user.cpp:17:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=1;j<A.size();++j) ^ user.cpp:19:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(A[i]==A[j] && j<A.size()) ^ user.cpp: In function ‘void solve()’: user.cpp:36:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<B.size();++i) ^ user.cpp:41:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k==A.size()) ^