Compilare: main.cpp: In function 'int main()': main.cpp:17:65: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(!res.empty() && res.top()<c[i] && res.size()-1+n-i>=k) ~~~~~~~~~~~~~~~~^~~ main.cpp:19:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(res.size()<k) ~~~~~~~~~~^~