Math Homework

Start from index 0 and move +1 or +2 at each step; stop as soon as the spread of the solved points first reaches threshold; if it can never be reached, solve the entire array as the problem states.

See "Input" for the standard input/output conventions and constraints added by this site.

输入格式

points is non-decreasing, n≤100000, and the values and threshold are in 1..999.

输出格式

Output the minimum number of problems; if the threshold cannot be reached, output n.

样例 1

输入：

5 4
1 2 3 5 8

输出：

3

样例 2

输入：

5 4
1 2 3 4 5

输出：

3

样例 3

输入：

4 10
4 5 6 7

输出：

4

样例 4

输入：

1 1
1

输出：

1