On her way to programming school tiger Dasha faced her first test — a huge staircase! [Image] 

The steps were numbered from one to infinity. As we know, tigers are very fond of all striped things, it is possible that it has something to do with their color. So on some interval of her way she calculated two values — the number of steps with even and odd numbers. 

You need to check whether there is an interval of steps from the l-th to the r-th (1 ≤ l ≤ r), for which values that Dasha has found are correct.


-----Input-----

In the only line you are given two integers a, b (0 ≤ a, b ≤ 100) — the number of even and odd steps, accordingly.


-----Output-----

In the only line print "YES", if the interval of steps described above exists, and "NO" otherwise.


-----Examples-----
Input
2 3

Output
YES

Input
3 1

Output
NO



-----Note-----

In the first example one of suitable intervals is from 1 to 5. The interval contains two even steps — 2 and 4, and three odd: 1, 3 and 5.

Difficulty: interview

Starter code:

Solutions:
a,b=list(map(int,input().split()))
print("YES"if abs(a-b)<=1 and a+b>0 else"NO")


a ,b = list(map(int, input().split()))
if a == 0 and b == 0:
    print('NO')
else:
    if abs(a - b) < 2:
        print('YES')
    else:
        print('NO')


a, b = list(map(int, input().split()))
if abs(a-b) <= 1 and (a,b) != (0,0):
    print("YES")
else:
    print("NO")


import math

a,b = [int(i) for i in input().split()]

if (a == 0 and b == 0) or abs(a-b) > 1:
    print('NO')
else:
    print('YES')


a, b = [int(x) for x in input().split()]
if a == 0 and b == 0:
    print("NO")
elif abs(a - b) <= 1:
    print("YES")
else:
    print("NO")


n,m=list(map(int,input().split()))
if(n+1==m or n-1==m or n==m):
	if(n==0 and m==0):
		print("NO")
	else:	
		print("YES")
else:
	print("NO")

    
    


#!/usr/bin/env python3
def ri():
    return list(map(int, input().split()))

a, b = ri()

if a == 0 and b == 0:
    print("NO")
    return

diff = abs(a-b)

if diff == 0 or diff == 1:
    print("YES")
else:
    print("NO")


import sys

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

def solve():
    a, b = map(int, input().split())

    if (a + b) > 0 and abs(a - b) <= 1:
        ans = 'YES'
    else:
        ans = 'NO'

    print(ans)

def __starting_point():
    solve()
__starting_point()

a, b = list(map(int, input().split()))
if a == b == 0:
    print('NO')
else:
    print('YES' if abs(a-b) <= 1 else 'NO')


a, b = map(int, input().split())
if abs(a - b) > 1 or a + b == 0:
    print("NO")
else:
    print("YES")


import sys, math

a, b = [int(x) for x in sys.stdin.readline().split()]

print('YES' if (a > 0 or b > 0) and math.fabs(a-b) <= 1 else 'NO')


a, b = map(int, input().split())

if abs(a - b) < 2 and a + b:
	print('YES')
else:
	print('NO')

import math

def __starting_point():
    
    a, b = list(map(int,input().split()))

    if a == 0 and b == 0:
        print("NO")
    elif a == b or a+1 == b or a == b+1:
        print("YES")
    else:
        print("NO")

__starting_point()

n, m = map(int, input().split())
if (abs(n - m) <= 1 and not(n == 0 and m == 0)):
    print('YES')
else:
    print('NO')

a, b = map(int, input().split())

if abs(a - b) > 1 or a == b == 0:
    print("NO")
else:
    print("YES")

a,b=list(map(int,input().split()))
if a==0 and b==0:
  print('NO')
else:
  print('YES' if abs(a-b)<=1 else 'NO')


n,m=input().split()
n,m=int(n),int(m)
if(m+n!=0):
    
    if((m-n)==1 or (m-n)==0 or (m-n)==-1) :
        print("YES")
    else:
        print("NO")
else:
        print("NO")


i, j = list(map(int, input().split()))

if not i and not j:
    print('NO')
else:
    if abs(i - j) > 1:
        print('NO')
    else:
        print('YES')


a, b = list(map(int,input().split()))

if abs(a - b) > 1 or (a == 0 and b == 0):
	print("NO")
else:
	print("YES")


a, b = map(int, input().split())
if a > b + 1:
    print("NO")
elif a == b == 0:
    print("NO")
elif b > a + 1:
    print("NO")
else:
    print("YES")

def main():
	a, b = map(int, input().split())
	if (abs(a - b) <= 1 and (a != 0 or b != 0)):
		print("YES")
	else:
		print("NO")


main()

a,b = list(map(int, input().split()))

if abs(a-b) <= 1 and (a > 0 or b > 0):
    print("YES")
else:
    print("NO")