Compilare: main.cpp: In function 'void DO()': main.cpp:66:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<P.size();++i) ~^~~~~~~~~ main.cpp: In function 'int main()': main.cpp:95:9: warning: unused variable 'i' [-Wunused-variable] int i,j; ^ main.cpp:95:11: warning: unused variable 'j' [-Wunused-variable] int i,j; ^