Compilare: main.cpp: In function 'std::__cxx11::string f(long long int, int)': main.cpp:54:47: warning: suggest parentheses around comparison in operand of '&' [-Wparentheses] while(e[j] < 0 && val & j == 0) ~~^~~~ main.cpp: In function 'std::__cxx11::string fb(std::__cxx11::string)': main.cpp:90:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i++) ~~^~~~~~~~~~