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

【链接】点击打开链接

【题意】

在这里写题意

【题解】

根据圆心到原点的距离这个东西判断一下圆在不在那个环里面就好

【错的次数】

0

【反思】

在这了写反思

【代码】

#include <cstdio>

#include <iostream>

#include <algorithm>

#include <cstring>

#include <vector>

#include <map>

#include <queue>

#include <iomanip>

#include <set>

#include <cstdlib>

#include <cmath>

using namespace std;

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1|1

#define LL long long

#define rep1(i,a,b) for (int i = a;i <= b;i++)

#define rep2(i,a,b) for (int i = a;i >= b;i--)

#define mp make_pair

#define pb emplace_back

#define fi first

#define se second

#define ld long double

#define ms(x,y) memset(x,y,sizeof x)

#define ri(x) scanf("%d",&x)

#define rl(x) scanf("%lld",&x)

#define rs(x) scanf("%s",x)

#define rf(x) scnaf("%lf",&x)

#define oi(x) printf("%d",x)

#define ol(x) printf("%lld",x)

#define oc putchar(' ')

#define os(x) printf(x)

#define all(x) x.begin(),x.end()

#define Open() freopen("F:\\rush.txt","r",stdin)

#define Close() ios::sync_with_stdio(0)

#define sz(x) ((int) x.size())

#define ld long double

typedef pair<int,int> pii;

typedef pair<LL,LL> pll;

//mt19937 myrand(time(0));

//int get_rand(int n){return myrand()%n + 1;}

const int dx[9] = {0,1,-1,0,0,-1,-1,1,1};

const int dy[9] = {0,0,0,-1,1,-1,1,-1,1};

const double pi = acos(-1.0);

const int N = 1e5;

struct abc{

    LL x,y,r;

};

LL R,D;

int n;

abc a[N+10];

LL sqr(LL x){

    return x*x;

}

int main(){

    //Open();

    //Close();

    rl(R),rl(D);

    ri(n);

    int ans = 0;

    rep1(i,1,n) {

        LL x,y,r;

        rl(x),rl(y),rl(r);

        LL temp = sqr(x)+sqr(y);

        long double temp1 = sqrt(temp)-r,temp2 = sqrt(temp)+r;

        if ( (R-D) <= temp1 && temp2 <= R) ans++;

    }

    oi(ans);puts("");

    return 0;

}