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 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#define MAXN 50
int main(void)
{
	int N;
	int p[MAXN];
	int i,j;
	int min;
	int cnt=0;
	int tmp;
	
	scanf("%d",&N);

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

	for(i=0;i<N-1;i++){
		min=i;
		for(j=i+1;j<N;j++){
			if(p[min]>p[j]){
				min=j;			
			}
		}
		if(p[min] != p[i]){
			tmp=p[i];
			p[i]=p[min];
			p[min]=tmp;	
			cnt++;
			for(j=0;j<N;j++){
				printf("%d ",p[j]);
			}printf("\n");

			if(cnt>1){
				puts("NO");
				return 0;
			}
		}
	}
	puts("YES");

	return 0;
}