a=int(input())
if (a<=0) and (a<=4):
    print('few')
elif (a<=9) and (a>=5):
    print("sveral")
elif (a<=19) and (a>=10):
    print("pack")
elif (a<=49) and (a>=20):
    print("lots")
elif (a<=99) and (a>=50):
    print('horde')
elif (a<=249) and (a>=100):
    print('throng')
elif (a<=499) and (a>=250):
    print('swarm')
elif (a<=999) and (a>=500):
    print("zounds")
elif a>=1000:
    print ('legion')

1) run test for 'few', like "3".
2) Why your conditions are so complicated?

if (a <= 4):
elif (a <= 9):
elif (a <= 19):
...