Compilare: main.cpp: In function 'int ok(int, int, long long unsigned int)': main.cpp:41:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(dr<s.size()-1) ~~^~~~~~~~~~~ main.cpp:48:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(cnt!=k) ~~~^~~ main.cpp:52:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a.size();i++) ~^~~~~~~~~ main.cpp:55:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i+n-1==a.size()) ~~~~~^~~~~~~~~~