Why "wrong answer"?
a=input()
if 0<a<5:
    print('few')
elif 4<a<10:
    print("sveral")
elif 9<a<20:
    print("pack")
elif 19<a<50:
    print("lots")
elif 49<a<100:
    print('horde')
elif 99<a<250:
    print('throng')
elif 249<a<500:
    print("swarm")
elif 499<a<1000:
    print("zounds")
elif 1000<a:
    print ('legion')

And if a=1000 ?

elif 999<a: