Compilare: main.cpp: In function 'void make_prefix()': main.cpp:27:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < a.size(); i++) { ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:48:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < b.size(); i++) { ~~^~~~~~~~~~ main.cpp:55:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (q == a.size()) { ~~^~~~~~~~~~~