Compilare: main.cpp: In function 'void pref()': main.cpp:18:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=2; i<=a.size(); i++) ~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:36:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<b.size(); i++) ~^~~~~~~~~ main.cpp:40:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(q==a.size()-1) ~^~~~~~~~~~~~ main.cpp:48:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<fin.size(); i++) out<<fin[i]<<' '; ~^~~~~~~~~~~