Compilare: main.cpp: In function 'int pref(int)': main.cpp:11:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 11 | while(j<v[i].size()&&j<v[i-1].size()&&v[i][j]==v[i-1][j]) | ~^~~~~~~~~~~~ main.cpp:11:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 11 | while(j<v[i].size()&&j<v[i-1].size()&&v[i][j]==v[i-1][j]) | ~^~~~~~~~~~~~~~