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 PyPy3 (2.4.0) (judge verdict: Runtime Error)

from math import ceil,sqrt,log,gcd,pi
def ii():return int(input())
def si():return input()
def mi():return map(int,input().split())
def li():return list(mi())

n=ii()
a=li()
b={}
for i in range(len(a)):
    b[a[i]]=i
a.sort()
x=[]
for i in range(n):
    if i!=b[a[i]]:
        x.append([i,b[a[i]]])
# print(x)
if(len(x)>2):
    print("No")
elif(len(x)==2 and x[0][0]!=x[1][1]):
    print('No')
else:
    print("Yes")