Compilare: main.cpp: In function 'int main()': main.cpp:70:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = enemies.size() - 1 ; i >= enemies.size() - (en - k2) - 1 ; i--) ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:27:12: warning: 'last' may be used uninitialized in this function [-Wmaybe-uninitialized] ll i , last; ^~~~