Ivan unexpectedly saw a present from one of his previous birthdays. It is array of n numbers from 1 to 200. Array is old and some numbers are hard to read. Ivan remembers that for all elements at least one of its neighbours ls not less than it, more formally:
a1≤a2,
an≤an−1 and
ai≤max(ai−1,ai+1) for all i from 2 to n−1.
Ivan does not remember the array and asks to find the number of ways to restore it. Restored elements also should be integers from 1 to 200. Since the number of ways can be big, print it modulo 998244353.
First line of input contains one integer n (2≤n≤105) — size of the array.
Second line of input contains n integers ai — elements of array. Either ai=−1 or 1≤ai≤200. ai=−1 means that i-th element can't be read.
Print number of ways to restore the array modulo 998244353.
3
1 -1 2
1
2
-1 -1
200
In the first example, only possible value of a2 is 2.
In the second example, a1=a2 so there are 200 different values because all restored elements should be integers between 1 and 200.
