4367: Increasing Sequence
金币值：2
定数：1
时间限制：2.000 s
内存限制：256 M
正确：0
提交：0
正确率：0.00% 命题人：
题目描述
time limit per test
1 secondmemory limit per test
64 megabytesinput
standard inputoutput
standard outputA sequence a0,a1,...,at-1 is called increasing if ai-1<ai for each i:0<i<t.
You are given a sequence b0,b1,...,bn-1 and a positive integer d. In each move you may choose one element of the given sequence and add d to it. What is the least number of moves required to make the given sequence increasing?
Input
The first line of the input contains two integer numbers n and d (2≤n≤2000,1≤d≤106). The second line contains space separated sequence b0,b1,...,bn-1 (1≤bi≤106).
Output
Output the minimal number of moves needed to make the sequence increasing.
Examples
Input
4 2
1 3 3 2
Output
3