Compilare: main.cpp: In function 'int main()': main.cpp:23:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<H[i].size(); j++) ~^~~~~~~~~~~~ main.cpp:33:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<H[i].size(); j++) ~^~~~~~~~~~~~ main.cpp:43:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<H[i].size(); j++) ~^~~~~~~~~~~~ main.cpp:32:16: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses] else if(op==2) ^