Compilare: main.cpp: In function 'void scan()': main.cpp:31:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<str.size(); ++i) ~^~~~~~~~~~~ main.cpp:41:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<str.size(); ++i) ~^~~~~~~~~~~ main.cpp:53:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<H[x].size(); ++j) ~^~~~~~~~~~~~