由于是程序菜鸡所以每一行都加了print打印变量，因此比较适合新手去阅读，程序大佬请不要嘲笑。
# coding=gbk
arr=input("")
num = [int(n) for n in arr.split()]
print(num)
num1={}
num2={}
i=1
k=0
x=0
t=0
s=0
a=0
i=0
len1=1
while t==0:
num2=num1
d1x=num[0]+1
print("dlx="+str(d1x))
i=1
len1=len(num)
if len1==1:
break
print("len1="+str(len1))
num1={}
while (i<d1x)&(i<len1):
num1[i-1]=num[i]-1
x=num1[i-1]
i=i+1
print("num1="+str(x))
while (i<len1):
if d1x>len1:
break
num1[i-1]=num[i]
print("bun1x="+str(num[i]))
i=i+1
print("num1="+str(num1))
num=num1
j=0
while j<len(num1):
print("num1s="+str(num[j]))
if num1[j]<0:
t=1
j=j+1
print(t)
print(t)
print("num2="+str(num2))
while s<len(num2):
if num2[s]%2==1:
a=a+1
if num2[s]>len(num2)+1:
i=1
s=s+1
if a%2==0&i==0:
print("yes")
else:
print("no")
