Compilare: main.cpp: In function 'int main()': main.cpp:32:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 32 | if (idx[i]<pref[i].size()) { | ~~~~~~^~~~~~~~~~~~~~~ main.cpp:49:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 49 | while (idx[i] < pref[i].size() && viz[pref[i][idx[i]]]) ++idx[i]; | ~~~~~~~^~~~~~~~~~~~~~~~