Codeforces Round #430 (Div. 2) B. Gleb And Pizza

B. Gleb And Pizza

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

Gleb ordered pizza home. When the courier delivered the pizza, he was very upset, because several pieces of sausage lay on the crust, and he does not really like the crust.

The pizza is a circle of radius r and center at the origin. Pizza consists of the main part — circle of radiusr - d with center at the origin, and crust around the main part of the widthd. Pieces of sausage are also circles. The radius of thei -th piece of the sausage is r_i, and the center is given as a pair (x_i,y_i).

Gleb asks you to help determine the number of pieces of sausage caught on the crust. A piece of sausage got on the crust, if it completely lies on the crust.

Input

First string contains two integer numbers r andd (0 ≤ d < r ≤ 500) — the radius of pizza and the width of crust.

Next line contains one integer number n — the number of pieces of sausage (1 ≤ n ≤ 10⁵).

Each of next n lines contains three integer numbersx_i,y_i andr_i ( - 500 ≤ x_i, y_i ≤ 500,0 ≤ r_i ≤ 500), wherex_i andy_i are coordinates of the center ofi-th peace of sausage, r_i — radius of i-th peace of sausage.

Output

Output the number of pieces of sausage that lay on the crust.

Examples

Input

8 477 8 1-7 3 20 2 10 -2 2-3 -3 10 6 25 3 1

Output

2

Input

10 840 0 90 0 101 0 11 0 2

Output

0

Note

Below is a picture explaining the first example. Circles of green color denote pieces of sausage lying on the crust.

水题，判断一下有多少个圆在环的里面

#include<iostream>#include<cmath>#include<cstdio>using namespace std;int main(){//freopen("in.txt","r",stdin);int r,d;cin>>r>>d;int n;cin>>n;int ans=0;while(n--){double x,y,dis;scanf("%lf%lf%lf",&x,&y,&dis);double a=x*x+y*y;double radiu=sqrt(a);if(radiu+dis<=r){if(radiu-dis>=r-d){ans++;}}}cout<<ans<<endl;}