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 C (GCC 9.2.1) (judge verdict: Accepted)

#include<stdio.h>

int main()
{
    int N=0,temp=0, i=0,j=0, counter=0,m=0;
    scanf("%d", &N);

    int arr[N];

    for(i=0; i<N; i++)
    {
        scanf(" %d", &arr[i]);
    }

    for(i=0; i<N; i++)
    {
        m=i;
        for(j=i+1; j<N; j++)
        {
            if(arr[j]<arr[m]) m=j;

        }
        if (m!=i) counter++;
        temp=arr[m];
        arr[m]=arr[i];
        arr[i]=temp;

    }

    for(i=0; i<N; i++)
    {
        if (arr[i]!=i+1) counter++;
    }



    if (counter<=1) printf("YES\n");
    else printf("NO\n");

    return 0;
}