Compilare: main.cpp: In function 'void formGN()': main.cpp:56:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < g[i].size(); ++j) ~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:94:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < gn[i].size(); ++j) ~~^~~~~~~~~~~~~~ main.cpp:106:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(it->gr == gc.size()-1) ~~~~~~~^~~~~~~~~~~~~~ main.cpp:112:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<gn[i].size(); j++) ~^~~~~~~~~~~~~