Compilare: main.cpp: In function 'void buildPre()': main.cpp:15:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 15 | while(j < x.size()) { | ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:40:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 40 | while(j < y.size()) { | ~~^~~~~~~~~~ main.cpp:45:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 45 | if(i == x.size()) { | ~~^~~~~~~~~~~ main.cpp:51:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 51 | } else if(i < x.size() && x[i] != y[j]) { | ~~^~~~~~~~~~