Compilare: main.cpp: In function 'int main()': main.cpp:47:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<v[1].size(); i++) ~^~~~~~~~~~~~ main.cpp:64:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<v[x].size(); j++) ~^~~~~~~~~~~~