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<stdio.h>
#include<stdlib.h>
#include<math.h>
typedef struct{
	int r,v;
	double x,y;
	double d;
}t_ufo;
t_ufo ufo[100];
int r,n;
int i,j;
int f[100];
int ans;
int next;

int main(){
	while(1){
		scanf("%d %d",&r,&n);
		if(r==0&&n==0)return 0;
		ans=0;
		for(i=0;i<n;i++){
			scanf("%lf %lf %d %d",&ufo[i].x,&ufo[i].y,&ufo[i].r,&ufo[i].v);
			ufo[i].d=sqrt(ufo[i].x*ufo[i].x+ufo[i].y*ufo[i].y);
		}
		for(i=0;i<n;i++)f[i]=true;
		while(1){
			next=-1;
			for(i=0;i<n;i++)if(f[i]){
				ufo[i].x=ufo[i].x*(ufo[i].d-ufo[i].v)/ufo[i].d;
				ufo[i].y=ufo[i].y*(ufo[i].d-ufo[i].v)/ufo[i].d;
				ufo[i].d-=ufo[i].v;
				if(ufo[i].d<=r){
					f[i]=false;
					ans++;
				}
				if(f[i]&&(next==-1||ufo[i].d<ufo[next].d))next=i;
			}
			if(next==-1)break;
			double tm,tc;
			tm=ufo[next].y;
			tc=ufo[next].x;
			f[next]=false;
			for(i=0;i<n;i++)if(f[i]){
				if((tm*ufo[i].x-tc*ufo[i].y)*(tm*ufo[i].x-tc*ufo[i].y)<=(ufo[i].r)*(ufo[i].r)*(tm*tm+tc*tc))f[i]=false;
			}
		}
		printf("%d\n",ans);
	}
}

C++: /*
 * src.cpp
 *
 *  Created on: 2016/08/01
 *      Author: joi
 */

#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,a) FOR(i,0,a)

const int MAX_N=1e2;
const double EPS=1e-10;

#define EQ(a,b) fabs(a-b)<EPS

int R,N;

struct Point{
	double x,y;
	Point(double x=0.0,double y=0.0):x(x),y(y){}
	Point operator +(const Point &p){
		return Point(x+p.x,y+p.y);
	}
	Point operator -(const Point &p){
		return Point(x-p.x,y-p.y);
	}
	Point operator *(double k){
		return Point(x*k,y*k);
	}
	Point operator /(double k){
		return Point(x/k,y/k);
	}
	double norm(){
		return x*x+y*y;
	}
	double abs(){
		return sqrt(norm());
	}
};

typedef pair<Point,Point> P;

typedef Point Vector;

double dot(const Vector &a,const Vector &b){
	return a.x*b.x+a.y*b.y;
}

double cross(const Vector &a,const Vector &b){
	return a.x*b.y-a.y*b.x;
}

struct Segment{
	Point p1,p2;
	Segment(Point p1=Point(),Point p2=Point()):p1(p1),p2(p2){}
};

typedef Segment line;

Point project(Segment s,Point p){
	Vector base=s.p2-s.p1;
	double r=dot(base,p-s.p1)/base.norm();
	return s.p1+base*r;
}

struct Circle{
	Point c;
	double r;
	Circle(Point c=Point(),double r=0.0):c(c),r(r){}
};

struct UFO{
	Circle cir;
	Vector v;
	bool flg;
};

UFO u[MAX_N];

P getCrossPoints(Circle c,line l){
	Point pr=project(l,c.c);
	Vector e=(l.p2-l.p1)/(l.p2-l.p1).abs();
	double base=sqrt(c.r*c.r-(c.c-pr).norm());
	return make_pair(pr+e*base,pr-e*base);
}

int main(){
	do{
		scanf("%d %d",&R,&N);
		if (R || N){
			REP(i,N){
				int x,y,r,v;
				scanf("%d %d %d %d",&x,&y,&r,&v);
				Vector p=Point((double)x,(double)y);
				u[i].cir=Circle(p,(double)r);
				u[i].flg=true;
				if (EQ(p.abs(),0)){
					u[i].v=Point(0.0,0.0);
				}else{
					u[i].v=p*(-1)/p.abs()*(double)v;
				}
			}
			while (1){
				REP(i,N){
					if (u[i].flg){
						if (u[i].cir.c.norm()<u[i].v.norm()-EPS){
							u[i].cir.c=Point(0.0,0.0);
						}else{
							u[i].cir.c=u[i].cir.c+u[i].v;
						}
					}
				}
				int a=-1;
				REP(i,N){
					if (u[i].flg){
						if (u[i].cir.c.norm()>R*R+EPS){
							if (a==-1 || u[i].cir.c.norm()<u[a].cir.c.norm()-EPS){
								a=i;
							}
						}
					}
				}
				if (a==-1){
					break;
				}
				line laser=Segment(Point(),u[a].cir.c);
				Vector e=u[a].cir.c/u[a].cir.c.abs();
				REP(i,N){
					if (u[i].flg){
						if (u[i].cir.c.norm()>R*R+EPS){
							Vector pr=project(laser,u[i].cir.c);
							if ((u[i].cir.c-pr).norm()<u[i].cir.r*u[i].cir.r-EPS){
								P pa=getCrossPoints(u[i].cir,laser);
								if (dot(e,pa.first)>=0 || dot(e,pa.second)>=0){
									u[i].flg=false;
								}
							}
						}
					}
				}
			}
			int ans=0;
			REP(i,N){
				if (u[i].flg){
					ans++;
				}
			}
			printf("%d\n",ans);
		}
	}while (R || N);
	return 0;
}