Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	x := make([]int, 100)
	y := make([]int, 100)
	r := make([]int, 100)
	for scanner.Scan() {
		a, _ := strconv.Atoi(scanner.Text())
		if a == 0 {
			break
		}
		for i := 0; i < a; i++ {
			scanner.Scan()
			input := strings.Split(scanner.Text(), " ")
			tmpx, _ := strconv.Atoi(input[0])
			tmpy, _ := strconv.Atoi(input[1])
			tmpr, _ := strconv.Atoi(input[2])
			x[i], y[i], r[i] = tmpx, tmpy, tmpr
		}
		scanner.Scan()
		b, _ := strconv.Atoi(scanner.Text())
		for i := 0; i < b; i++ {
			scanner.Scan()
			input := strings.Split(scanner.Text(), " ")
			c, _ := strconv.Atoi(input[0])
			d, _ := strconv.Atoi(input[1])
			e, _ := strconv.Atoi(input[2])
			f, _ := strconv.Atoi(input[3])
			ok := false
			for j := 0; j < a; j++ {
				if (c-x[j])*(c-x[j])+(d-y[j])*(d-y[j]) >= r[j]*r[j] || (e-x[j])*(e-x[j])+(f-y[j])*(f-y[j]) >= r[j]*r[j] {
					if (e-c)*(x[j]-c)+(f-d)*(y[j]-d) < 0 {
						if (x[j]-c)*(x[j]-c)+(y[j]-d)*(y[j]-d) <= r[j]*r[j] {
							ok = true
						}
					} else {
						if (e-c)*(x[j]-c)+(f-d)*(y[j]-d)>(e-c)*(e-c)+(f-d)*(f-d) {
							if (x[j]-e)*(x[j]-e)+(y[j]-f)*(y[j]-f)<=r[j]*r[j] {
								ok = true
							}
						} else {
							if (x[j]-c)*(x[j]-c)+(y[j]-d)*(y[j]-d)-((e-c)*(x[j]-c)+(f-d)*(y[j]-d))*((e-c)*(x[j]-c)+(f-d)*(y[j]-d))/((e-c)*(e-c)+(f-d)*(f-d))<=r[j]*r[j] {
								ok = true
							}
						}
					}

				}
			}
			if ok {
				fmt.Println("Safe")
			} else {
				fmt.Println("Danger")
			}
		}
	}
}

C++: #include<stdio.h>
#include<cmath>
#include<algorithm>
using namespace std;
const double EPS=1e-10;

double add(double a,double b){return a+b;}
typedef struct Vec{
	double x,y;
	Vec(){}
	Vec(double x,double y):x(x),y(y){}
	Vec operator +(Vec v){return Vec(add(x,v.x),add(y,v.y));}
	Vec operator -(Vec v){return Vec(add(x,-v.x),add(y,-v.y));}
}Vec;
typedef struct Cer{double r;Vec cp;}Cer;


double dot(Vec a,Vec b){return a.x*b.x+a.y*b.y;}
double det(Vec a,Vec b){return a.x*b.y-a.y*b.x;}
double vabs(Vec a){return hypot(a.x,a.y);}
Vec dis(Vec a,Vec b){return Vec(a.x-b.x,a.y-b.y);}
double ch(Vec a,Vec b,Vec c)
{
	if(dot(b-a,c-a)<EPS)return vabs(b-a);
	if(dot(a-b,c-b)<EPS)return vabs(c-b);
	return fabs(det(b-a,c-a))/vabs(b-a);
}

int N,M,i,j,f;
double m,d;
Cer W[100];

int main()
{
	for(;scanf("%d",&N),N;)
	{
		for(i=0;i<N;i++)
			scanf("%lf%lf%lf",&W[i].cp.x,&W[i].cp.y,&W[i].r);
		scanf("%d",&M);
		for(i=0;i<M;i++)
		{
			f=0;
			Vec t,s;
			scanf("%lf%lf%lf%lf",&t.x,&t.y,&s.x,&s.y);
			for(j=0;j<N;j++)
			{
				if(vabs(dis(s,W[j].cp))<=W[j].r&&vabs(dis(t,W[j].cp))<=W[j].r)continue;
				if(ch(t,s,W[j].cp)<=W[j].r)
					f=1;
			}
			puts(f?"Safe":"Danger");
		}
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

typedef complex<double> P;
typedef pair<double, P> C;
vector<C> circles;
#define FST first
#define SND second
typedef pair<P, P> S;
#define EPS (1e-5)

double dot(P a, P b) {
  return a.real()*b.real()+a.imag()*b.imag();
}

double cross(P a, P b) {
  return a.real()*b.imag()-a.imag()*b.real();
}

double distanceLP(S s, P a) {
  // d = |y||sin(th)| = |x||y|sin(th)/|x| = |cross(x, y)|/|x|
  return abs(cross(s.SND-s.FST, a-s.FST)) / abs(s.SND-s.FST);
}

double distanceSP(S s, P a) {
  // 2ベクトルのなす角が鈍角なら端点と１点との距離を返す
  if (dot(s.SND-s.FST, a-s.FST) < EPS) return abs(a-s.FST);
  if (dot(s.FST-s.SND, a-s.SND) < EPS) return abs(a-s.SND);
  
  return distanceLP(s, a);
}

int main() {
  int N;
  while(cin >> N && N) {
    circles.clear();
    circles.resize(N);
    for(int i=0; i<N; i++) {
      int x, y, r;
      cin >> x >> y >> r;
      circles[i] = C(r, P(x, y));
    }
    int Q; cin >> Q;
    while(Q--) {
      int x, y;
      cin >> x >> y; P taro(x, y);
      cin >> x >> y; P ogre(x, y);
      for(int i=0; i<N; i++) {
	if(distanceSP(S(taro, ogre), circles[i].SND) < circles[i].FST + EPS) {
	  if(   !(abs(circles[i].SND-taro) < circles[i].FST + EPS)
	     || !(abs(circles[i].SND-ogre) < circles[i].FST + EPS)) {
	    cout << "Safe" << endl;
	    goto EXIT;
	  }
	}
      }
      
      cout << "Danger" << endl;
      
    EXIT:;
    }
  }
  
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

typedef complex<double> P;
typedef pair<double, P> C;
vector<C> circles;
#define FST first
#define SND second
typedef pair<P, P> S;
#define EPS (1e-5)

double dot(P a, P b) {
  return a.real()*b.real()+a.imag()*b.imag();
}

double cross(P a, P b) {
  return a.real()*b.imag()-a.imag()*b.real();
}

double distanceLP(S s, P a) {
  // d = |y||sin(th)| = |x||y|sin(th)/|x| = |cross(x, y)|/|x|
  return abs(cross(s.SND-s.FST, a-s.FST)) / abs(s.SND-s.FST);
}

double distanceSP(S s, P a) {
  // 2ベクトルのなす角が鈍角なら端点と１点との距離を返す
  if (dot(s.SND-s.FST, a-s.FST) < EPS) return abs(a-s.FST);
  if (dot(s.FST-s.SND, a-s.SND) < EPS) return abs(a-s.SND);
  
  return distanceLP(s, a);
}

int main() {
  int N;
  while(cin >> N && N) {
    circles.clear();
    circles.resize(N);
    for(int i=0; i<N; i++) {
      int x, y, r;
      cin >> x >> y >> r;
      circles[i] = C(r, P(x, y));
    }
    int Q; cin >> Q;
    while(Q--) {
      int x, y;
      cin >> x >> y; P taro(x, y);
      cin >> x >> y; P ogre(x, y);
      for(int i=0; i<N; i++) {
        if(distanceSP(S(taro, ogre), circles[i].SND) < circles[i].FST + EPS) {
          if(  abs(circles[i].SND-taro) > circles[i].FST + EPS
	    || abs(circles[i].SND-ogre) > circles[i].FST + EPS) {
            cout << "Safe" << endl;
            goto EXIT;
          }
        }
      }
      
      cout << "Danger" << endl;
      
    EXIT:;
    }
  }
  
  return 0;
}