Compilare: main.cpp: In function 'int main()': main.cpp:29:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j<a[y].size()&&fr[a[y][j]]==0) j++; ~^~~~~~~~~~~~ main.cpp:32:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j<a[y].size()&&fr[a[y][j]]==0) j++; ~^~~~~~~~~~~~