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)

import sys
def printans(t):
    print(t)
    sys.exit()

N=int(input())
A=[int(i) for i in input().split()]

if all([a==A[0] for a in A]):#全部同じ
    shurui=A[0]
    if shurui==N-1 or shurui*2<=N:
        printans("Yes")
    else:printans("No")
else:#少ないやつは自分だけの色、そいつら以外で上と同じ処理
    maxshurui = max(A)
    if all([a in (maxshurui,maxshurui-1) for a in A]):
        unique = A.count(maxshurui-1)
        shurui = maxshurui-unique
        if shurui<=0:
            printans("No")
        if shurui*2<=N-unique:
            printans("Yes")
        else:printans("No")
    else:printans("No")