Compilare: main.cpp: In function 'int main()': main.cpp:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if ( a.size() > U ) s -= a.front(), a.pop_front(); ~~~~~~~~~^~~ main.cpp:32:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while ( a.front() <= 0 && a.size() >= L ) s -= a.front(), a.pop_front(); ~~~~~~~~~^~~~