Lesha and array splitting

Description:

Input:

The first line contains single integer n (1 ≤ n ≤ 100) — the number of elements in the array A.

The next line contains n integers a₁, a₂, ..., a_n ( - 10³ ≤ a_i ≤ 10³) — the elements of the array A.

Output:

If it is not possible to split the array A and satisfy all the constraints, print single line containing "NO" (without quotes).

Otherwise in the first line print "YES" (without quotes). In the next line print single integer k — the number of new arrays. In each of the next k lines print two integers l_i and r_i which denote the subarray A[l_i... r_i] of the initial array A being the i-th new array. Integers l_i, r_i should satisfy the following conditions:

• l₁ = 1
• r_k = n
• r_i + 1 = l_i + 1 for each 1 ≤ i < k.

If there are multiple answers, print any of them.

Sample Input:

3
1 2 -3

Sample Output:

YES
2
1 2
3 3

Sample Input:

8
9 -12 3 4 -4 -10 7 3

Sample Output:

YES
2
1 2
3 8

Sample Input:

1
0

Sample Output:

NO

Sample Input:

4
1 2 3 -5

Sample Output:

YES
4
1 1
2 2
3 3
4 4