Go: package main

import (
	"bufio"
	"os"
	"math"
	"strings"
	"strconv"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

const (
	INF = 0x7FFFFFFF
	EPS = 1e-10
)

type Point struct {
	x, y float64
}
func (p *Point) plus(q *Point) *Point {
	return &Point{p.x + q.x, p.y + q.y}
}
func (p *Point) minus(q *Point) *Point {
	return &Point{p.x - q.x, p.y - q.y}
}
func (p *Point) multi(a float64) *Point {
	return &Point{p.x * a, p.y * a}
}
func (p *Point) div(a float64) *Point {
	return &Point{p.x / a, p.y / a}
}
func (p *Point) abs() float64 {
	return math.Sqrt(p.norm())
}
func (p *Point) norm() float64 {
	return p.x*p.x + p.y*p.y
}
func (p *Point) isLessThan(q *Point) bool {
	if p.x != q.x {
		return p.x < q.x && p.y < q.y
	}
	return true
}
func (p *Point) isEqual(q *Point) bool {
	return math.Abs(p.x - q.x) < EPS && math.Abs(p.y - q.y) < EPS
}

type Segment struct {
	p1, p2 *Point
}
func (s *Segment) norm() float64 {
	return (s.p2.x - s.p1.x)*(s.p2.x - s.p1.x) +
		(s.p2.y - s.p1.y)*(s.p2.y - s.p1.y)
}
func (s *Segment) abs() float64 {
	return math.Sqrt(s.norm())
}

func norm(a *Point) float64 {
	return a.x*a.x + a.y*a.y
}

func abs(a *Point) float64 {
	return math.Sqrt(norm(a))
}

func polar(a, r float64) *Point {
	return &Point{math.Cos(r)*a, math.Sin(r)*a}
}

func getDistance(a, b *Point) float64 {
	return abs(a.minus(b))
}

func dot(a, b *Point) float64 {
	return a.x*b.x + a.y*b.y
}

func cross(a, b *Point) float64 {
	return a.x*b.y - a.y*b.x
}

func getDistanceLP(s Segment, p *Point) float64 {
	return cross(s.p2.minus(s.p1), p.minus(s.p1))/ abs(s.p2.minus(s.p1))
}

func getDistanceSP(s Segment, p *Point) float64 {
	if dot(s.p2.minus(s.p1), p.minus(s.p1)) < 0 {
		return abs(p.minus(s.p1))
	}
	if dot(s.p1.minus(s.p2), p.minus(s.p2)) < 0 {
		return abs(p.minus(s.p2))
	}
	return getDistanceLP(s, p)
}

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		R, _ := strconv.Atoi(buf[0])
		N, _ := strconv.Atoi(buf[1])
		if R == 0 && N == 0 {
			break
		}
		p := make([]*Point, N)
		r := make([]float64, N)
		v := make([]float64, N)
		d := make([]float64, N)
		nd := make([]float64, N)
		die := make([]bool, N)
		for i := 0; i < N; i++ {
			scanner.Scan()
			buf_ := strings.Split(scanner.Text(), " ")
			_x, _ := strconv.ParseFloat(buf_[0], 64)
			_y, _ := strconv.ParseFloat(buf_[1], 64)
			_r, _ := strconv.ParseFloat(buf_[2], 64)
			_v, _ := strconv.ParseFloat(buf_[3], 64)
			tmp := &Point{_x, _y}
			p[i] = tmp
			r[i] = _r
			v[i] = _v
			nd[i] = getDistance(p[i], &Point{0, 0})
			d[i] = getDistance(p[i], &Point{0, 0})
			die[i] = false
		}
		for {
			for i := 0; i < N; i++ {
				nd[i] = math.Max(float64(R), nd[i]-v[i])
			}
			mini := float64(INF)
			id := -1
			for i := 0; i < N; i++ {
				if die[i] {
					continue
				}
				if nd[i] < EPS+float64(R) {
					continue
				}
				if nd[i] > mini {
					continue
				}
				mini = nd[i]
				id = i
			}
			if id == -1 {
				break
			}
			s := Segment{p[id], p[id]}
			s.p1 = s.p1.div(d[id])
			s.p1 = s.p1.multi(float64(R))
			s.p2 = s.p2.div(d[id])
			s.p2 = s.p2.multi(10000000.0)
			for i := 0; i < N; i++ {
				if nd[i] < EPS + float64(R) {
					continue
				}
				a := p[i]
				a = a.div(d[i])
				a = a.multi(nd[i])
				if getDistanceSP(s, a) < EPS + r[i] {
					die[i] = true
				}
			}
		}
		ans := 0
		for i := 0; i < N; i++ {
			if !die[i] {
				ans++
			}
		}
		fmt.Println(ans)
	}
}

C++: #include <iostream>
#include <complex>
#include <vector>
#include <algorithm>
#include <utility>
#include <cmath>
using namespace std;
typedef complex<double> P;
typedef pair<P, P> L;
typedef pair<P, double> C;
#define X real()
#define Y imag()
const double INF = 1e9;
const double EPS = 1e-10;

double dot(P a, P b){return a.X*b.X + a.Y*b.Y;}

double cross(P a, P b){return a.X*b.Y - a.Y*b.X;}

int ccw(P a, P b, P c){
  b -= a;
  c -= a;
  if(cross(b, c) > EPS) return 1;
  if(cross(b, c) < -EPS) return -1;
  if(dot(b, c) < -EPS) return -2;
  if(norm(c) > norm(b) + EPS) return 2;
  return 0;
}

P projection(P a, P b){
  return dot(a, b)/norm(b)*b;
}

bool is_attacked(C ufo, P d, int R){
  return (abs(projection(ufo.first, d)) > R - EPS && abs(cross(ufo.first, d)) < ufo.second + EPS);
}

int main(){
  int R, N;
  while(cin >> R >> N){
    if(R == 0 && N == 0) break;
    vector<C> UFO(N);
    vector<int> V(N);
    for(int i = 0; i < N; ++i){
      double x, y, r;
      cin >> x >> y >> r >> V[i];
      UFO[i] = C(P(x, y), r);
    }
    int c = 0, ans = 0, t = 0;
    vector<bool> U(N, false);
    while(c < N){
      ++t;
      double closest = INF;
      int id = -1;
      for(int i = 0; i < N; ++i){
        if(U[i]) continue;
        if(abs(UFO[i].first) - t*V[i] < closest){
          if(abs(UFO[i].first) - t*V[i] <= R + EPS){
            ++c;
            ++ans;
            U[i] = true;
          }else{
            closest = abs(UFO[i].first) - t*V[i];
            id = i;
          }
        }
      }
      if(id < 0) continue;
      P d = UFO[id].first;
      U[id] = true;
      ++c;
      for(int i = 0; i < N; ++i){
        if(U[i]) continue;
        if(is_attacked(UFO[i], d, R)){
          U[i] = true;
          ++c;
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}

C++: // 2011/08/01 Tazoe

#include <iostream>
#include <cmath>
using namespace std;

struct ufo{
	int x;
	int y;
	int r;
	int v;

	int sta;
	double dis;
};

int main()
{
	while(true){
		int R, N;
		cin >> R >> N;
		if(R==0&&N==0)
			break;

		struct ufo U[100];
		for(int i=0; i<N; i++){
			cin >> U[i].x >> U[i].y >> U[i].r >> U[i].v;

			U[i].sta = 0;
			U[i].dis = sqrt((double)(U[i].x*U[i].x+U[i].y*U[i].y));
		}
/*
		for(int i=0; i<N; i++)
			cout << U[i].sta << ' ' << U[i].dis << endl;
*/
		int n = 0;
		int m = 0;
		while(true){
			double min_dis = 1500.0;
			int    min_i   = -1;
			for(int i=0; i<N; i++){
				if(U[i].sta==0){
					U[i].dis -= (double)U[i].v;
					if(U[i].dis<=(double)R){
						U[i].sta = 1;
						n++;
					}
					else if(U[i].dis<min_dis){
						min_dis = U[i].dis;
						min_i   = i;
					}
				}
			}

			if(min_i!=-1){
				U[min_i].sta = 2;
				m++;

				for(int i=0; i<N; i++){
					if(U[i].sta==0){
						if((double)U[i].r>=U[i].dis){
							U[i].sta = 2;
							m++;
						}
						else{
							double cos1 = (double)(U[i].x*U[min_i].x+U[i].y*U[min_i].y)/(sqrt((double)(U[i].x*U[i].x+U[i].y*U[i].y))*sqrt((double)(U[min_i].x*U[min_i].x+U[min_i].y*U[min_i].y)));
							double cos2 = sqrt(1.0-(double)(U[i].r*U[i].r)/(U[i].dis*U[i].dis));
							if(cos1>=cos2){
								U[i].sta = 2;
								m++;
							}
						}
					}
				}
			}
/*
			for(int i=0; i<N; i++)
				cout << U[i].sta << ' ' << U[i].dis << endl;
*/
			if(n+m==N)
				break;
		}

		cout << n << endl;
	}

	return 0;
}