Compilare: main.cpp: In function 'std::__cxx11::string mergeStr(std::__cxx11::string, std::__cxx11::string)': main.cpp:17:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(interact(pref + a[0] + b) == pref.size() + 1 + b.size()) { ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:38:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < str[0].size(); i += 2) ~~^~~~~~~~~~~~~~~