【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;
}