Compilare: main.cpp: In function 'int main()': main.cpp:11:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<ch.size(); i++) ~^~~~~~~~~~ main.cpp:13:20: warning: array subscript has type 'char' [-Wchar-subscripts] frecv[ch[i]]++; ^ main.cpp:15:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<ch.size(); i++) ~^~~~~~~~~~ main.cpp:26:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(nr>(ch.size()-i)/2) ~~^~~~~~~~~~~~~~~~