p00340 Rectangle
The educational program (AHK Education) of the Aiz Broadcasting Association broadcasts a handicraft program for children, "Play with Tsukuro". Today is the time to make a rectangle with sticks, but I would like to see if I can make a rectangle using the four sticks I prepared. However, the stick must not be cut or broken.




Given the lengths of the four bars, write a program to determine if you can make a rectangle with all of them as sides.



Input

The input is given in the following format.


e1 e2 e3 e4


The input consists of one line and is given the integer ei (1 ≤ ei ≤ 100) representing the length of each bar.

Output

Outputs "yes" if a rectangle can be created, and "no" if it cannot be created. However, since a square is a type of rectangle, "yes" is output even if it is a square.

Examples

Input

1 1 3 4


Output

no


Input

1 1 2 2


Output

yes


Input

2 1 1 2


Output

yes


Input

4 4 4 10


Output

no
```python
s = input().split()
for j in range(len(s)):
  for k in range(j-1,-1,-1):
    if s[k] >= s[k+1]:
      s[k],s[k+1] = s[k+1],s[k]
if s[1] == s[0]:
  if s[2] == s[3]:
    print("yes")
  else:
    print("no")
else:
  print("no")

```