求帮助，不知从何下手，只知道会用到循环结构

d = []
while True:
    n = int(input(">>>"))
    if n == -1 :break
    d.append(n)
    
for i in d:
    if i == 1 or i == 2 :
        print("even")
        continue
    a = [1, 1]
    
    for _ in range(i - 2):
        a.append(a[0+_] + a[1+_])

    if a[-1] % 2 == 0 :
        print("odd")
    else:
        print("even")