Problem:
Score : 200 points

Problem Statement

We have a sequence p = {p_1,\ p_2,\ ...,\ p_N} which is a permutation of {1,\ 2,\ ...,\ N}.

You can perform the following operation at most once: choose integers i and j (1 \leq i < j \leq N), and swap p_i and p_j. Note that you can also choose not to perform it.

Print YES if you can sort p in ascending order in this way, and NO otherwise.

Constraints

All values in input are integers.

2 \leq N \leq 50

p is a permutation of {1,\ 2,\ ...,\ N}.

Input

Input is given from Standard Input in the following format:

N
p_1 p_2 ... p_N

Output

Print YES if you can sort p in ascending order in the way stated in the problem statement, and NO otherwise.

Sample Input 1

5
5 2 3 4 1

Sample Output 1

YES

You can sort p in ascending order by swapping p_1 and p_5.

Sample Input 2

5
2 4 3 5 1

Sample Output 2

NO

In this case, swapping any two elements does not sort p in ascending order.

Sample Input 3

7
1 2 3 4 5 6 7

Sample Output 3

YES

p is already sorted in ascending order, so no operation is needed.

Solution in Python (3.4.3) (judge verdict: Wrong Answer)

"""
# 標準入力取得
## 文字列
     = sys.stdin.readline().rstrip()
     = list(sys.stdin.readline().rstrip())

## 数値
     = int(sys.stdin.readline())
     = map(int, sys.stdin.readline().split())
     = list(map(int, sys.stdin.readline().split()))
     = [list(map(int,list(sys.stdin.readline().split()))) for i in range(h)]  # 二次元配列入力　二次元マップみたいな入力のとき

# 0埋め, 小数点出力桁指定時のときの出力
a = 100
b = 0.987654321
print("{0:06d}-{1:6f}".format(a,b))
000100-0.987654

# 文字列をリストに格納
char_list = list("abcd") # ["a","b","c","d"]
"""

import math
import sys
import itertools
import queue
from fractions import gcd

import copy

def lcm(a, b):
    return a * b // gcd(a, b)

mod = 1000000007
# sortedと比較
# 
if __name__ == "__main__":
     _ = int(sys.stdin.readline())
     L = list(map(int, sys.stdin.readline().split()))
     Ls = sorted(L)
     
     if L == Ls:
          print("YES")
          exit()
     
     mai = L.index(max(L))
     mii = L.index(min(L))

     tmp = L[mai]
     L[mai] = L[mii]
     L[mii] = tmp

     if L == Ls:
          print("YES")
     else:
          print("NO")