Problem:
Score : 700 points

Problem Statement

There are N cats.
We number them from 1 through N.

Each of the cats wears a hat.
Cat i says: "there are exactly a_i different colors among the N - 1 hats worn by the cats except me."

Determine whether there exists a sequence of colors of the hats that is consistent with the remarks of the cats.

Constraints

2 ≤ N ≤ 10^5

1 ≤ a_i ≤ N-1

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print Yes if there exists a sequence of colors of the hats that is consistent with the remarks of the cats; print No otherwise.

Sample Input 1

3
1 2 2

Sample Output 1

Yes

For example, if cat 1, 2 and 3 wears red, blue and blue hats, respectively, it is consistent with the remarks of the cats.

Sample Input 2

3
1 1 2

Sample Output 2

No

From the remark of cat 1, we can see that cat 2 and 3 wear hats of the same color.
Also, from the remark of cat 2, we can see that cat 1 and 3 wear hats of the same color.
Therefore, cat 1 and 2 wear hats of the same color, which contradicts the remark of cat 3.

Sample Input 3

5
4 3 4 3 4

Sample Output 3

No

Sample Input 4

3
2 2 2

Sample Output 4

Yes

Sample Input 5

4
2 2 2 2

Sample Output 5

Yes

Sample Input 6

5
3 3 3 3 3

Sample Output 6

No

Solution in Python (3.4.3) (judge verdict: Accepted)

n = int(input())
a = list(map(int, input().split()))
import collections
l1 = collections.Counter(a).most_common()
l1.sort()
if len(l1) > 2:
    print("No")
elif len(l1) == 1:#発言が１種類の場合
    if l1[0][0] * 2 <= n or l1[0][0] == n - 1:
        print("Yes")
    else:
        print("No")
else:
    if l1[1][0] - l1[0][0] > 1:
        print("No")
    elif l1[1][1] >= (l1[1][0] - l1[0][1]) * 2 and l1[1][0] > l1[0][1]:
        print("Yes")#多い発言の人数が残りの色数かけ２より多い、全体色数が少ない発言の人数より多い
    else:
        print("No")