13:I[87,["736","static/chunks/89fc4f0e-9e200ae6a0166583.js","401","static/chunks/363642f4-32903b9154b7835a.js","153","static/chunks/153-58eddeb032cc4608.js","131","static/chunks/131-05ce00cfd760e12b.js","87","static/chunks/87-b76b60eef573119a.js","286","static/chunks/app/problem/%5Bid%5D/page-45cf3875257fc32e.js"],"Header"] 14:I[1742,["736","static/chunks/89fc4f0e-9e200ae6a0166583.js","401","static/chunks/363642f4-32903b9154b7835a.js","153","static/chunks/153-58eddeb032cc4608.js","131","static/chunks/131-05ce00cfd760e12b.js","87","static/chunks/87-b76b60eef573119a.js","286","static/chunks/app/problem/%5Bid%5D/page-45cf3875257fc32e.js"],"ProblemView"] 15:T618,

This is an unusual problem in an unusual contest, here is the announcement: http://codeforces.com/blog/entry/73543

You run a string shop. During a day your customers want to buy strings of certain lengths and sometimes satisfying other properties.

Today your first customer asked you if you have a string of length $$$k$$$. In fact, you have a string of length $$$n$$$ and can cut a string of length $$$k$$$ starting at any position out of it. You wonder how many distinct values this string can equal.

Please note that in your shop strings are over an alphabet of size $$$2$$$.

Input

The first line contains two integers $$$n$$$ and $$$k$$$ ($$$1\leq k\leq n\leq 200\,000$$$). The second line contains a binary string $$$s$$$ of length $$$n$$$.

Output

In the only line print the number of distinct substrings of length $$$

Deja vu

Examples