city(abilene, 1718);
city("addis ababa", 8000);
city(denver, 5280);
city(flagstaff, 6970);
city(jacksonville, 8);
city(leadville, 10200);
city(madrid, 1305);
city(richmond, 19);
city(spokane, 1909);
city(wichita, 1305); 
highCity(Name) :- city(Name, Alt), >(Alt, 5000);

