states_needed=set(["mt","wa","or","id","nv","ut","ca","az"])
stations ={}
stations["kone"]=set(["id","nv","ut"])
stations["ktwo"]=set(["id","wa","mt"])
stations["kthree"]=set(["or","nv","ca"])
stations["kfour"]=set(["nv","ut"])
stations["kfive"]=set(["ca","az"])
final_station=set()
while states_needed:
    best_station=None
    state_covered=set()
    for station,state in stations.items():
        covered=states_needed & state
        if len(covered)>len(state_covered):
            best_station=station
            state_covered=covered
    final_station.add (best_station)
    states_needed-=state_covered

print( final_station)