Compilare: In file included from /usr/include/c++/4.8/cassert:43:0, from user.cpp:4: user.cpp: In function ‘int main()’: user.cpp:24:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] assert(L[k1].size() > x1); ^ user.cpp:25:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] assert(L[k2].size() >= x2); ^ user.cpp:28:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (L[k1].size() <= x1) continue; ^ user.cpp:29:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (L[k2].size() < x2) continue; ^ user.cpp:37:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < L[k].size(); i++) ^