Compilare: main.cpp: In function 'int main()': main.cpp:61:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < e.size(); ++i) { ~~^~~~~~~~~~ main.cpp:64:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < e[i].size(); ++j) fout << e[i][j] << " "; ~~^~~~~~~~~~~~~