两数之和python

ls = list(map(int, input().split()))
n = int(input())
count = 0
d = 0
for i in ls:
    b = n - i
    count = count + 1
    if b in ls[count:]:
        print(count - 1, count + ls[count:].index(b))
        break

else:
    print('Fail')