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 <iostream>
#include <map>
#include <queue>
#include <algorithm>
#include <complex>
#include <cassert>

using namespace std;
typedef long long ll;

typedef long double R;
typedef complex<R> P;


namespace std {
    bool operator < (P a, P b) {
        return real(a) != real(b) ? real(a) < real(b) : imag(a) < imag(b);
    }
    bool operator > (P a, P b) {
        return (b < a);
    }
}

const R EPS = 1e-7;
const R PI = acos(-1);

int sgn(R a) {
    if (a < -EPS) return -1;
    if (a > EPS) return 1;
    return 0;
}


bool near(P a, P b) {
    return !sgn(abs(a-b));
}

R cross(P a, P b) { return imag(conj(a)*b); }
R dot(P a, P b) { return real(conj(a)*b); }

/* 1->cclock
  -1->clock
   0->on
   2->back
  -2->front
  */
int ccw(P a, P b, P c) {
    assert(!near(a, b));
    if (near(a, c) || near(b, c)) return 0;
    int s = sgn(cross(b-a, c-a));
    if (s) return s;
    if (a > b) swap(a, b);
    if (dot(b-a, c-a) < 0) return 2;
    if (dot(a-b, c-b) < 0) return -2;
//    if (c < a) return 2;
//    if (b < c) return -2;
    return 0;
}

struct L {
    P x, y;
    L() {};
    L(P x, P y) :x(x), y(y) {};
};

P vec(const L &l) {
    return l.y - l.x;
}

R abs(const L &l) {
    return abs(vec(l));
}



struct C {
    P p;
    R r;
    C () {};
    C (P p, R r) : p(p), r(r) {};
};

R distLP(const L &l, const P &p) {
	assert(!near(l.x, l.y));
    return abs(cross(vec(l), p-l.x)/abs(l));
}

//need Intersect/distLP
int crossP(const C &c, const L &l, L &r) {
    R u = distLP(l, c.p);
    int si = sgn(u - c.r);
    if (si == 1) return 0;
    P v = (l.y-l.x) / abs(l) * P(0, -1); //l?????´???????????????????????????
    v *= u;
    if (ccw(l.x, l.y, c.p) < 0) v *= -1;
    //v?????????????????????l?????¨??????????????????????????????
    if (si == 0) {
        r.x = r.y = c.p + v;
        return 1;
    }
    r.x = c.p+v+polar<R>(sqrt(c.r*c.r - u*u), arg(vec(l)));
    r.y = c.p+v-polar<R>(sqrt(c.r*c.r - u*u), arg(vec(l)));
    return 2;
}


C ci[110];
int main() {
	while (true) {
		int n;
		cin >> n;
		if (!n) break;
		for (int i = 0; i < n; i++) {
			R x, y, r;
			cin >> x >> y >> r;
			ci[i] = C(P(x, y), r);
			assert(r);
		}
		int m;
		cin >> m;
		for (int i = 0; i < m; i++) {
			R tx, ty, sx, sy;
			cin >> tx >> ty >> sx >> sy;
			P t = P(tx, ty), s = P(sx, sy);

			bool f = true;
			for (int j = 0; j < n; j++) {
				L l;
				int cp = crossP(ci[j], L(t, s), l);
//				printf("%d %d %d\n", i, j, cp);
				if (!cp) continue;
//				cout << l.x << " " << l.y << endl;
//				cout << t << " " << s << " " << l.x << " " << ccw(t, s, l.x) << endl;
				if (!ccw(t, s, l.x) || !ccw(t, s, l.y)) {
					f = false;
					break;
				}
			}
			if (f) {
				cout << "Danger" << endl;
			} else {
				cout << "Safe" << endl;
			}
		}
	}
	return 0;
}

C++: #include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <utility>
#include <functional>
#include <sstream>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
#include <fstream>
#include <list>
using namespace std;
inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v;}
template<class T> inline string toStr(T x) { ostringstream sout; sout << x; return sout.str();}
typedef vector<int> vi;
typedef vector<vi>  vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)
#define REP(i,n) FOR(i,0,(n)-1)
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INF = INT_MAX/10;

#include <complex>
typedef complex<double> P;
typedef vector<P> vp;
typedef vector<double> vd;

#define LT(x,y) ((x)-(y)<=-EPS)
#define LE(x,y) ((x)-(y)<+EPS)

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 dist(P a, P b) {
	return abs(b-a);
}

double distance_ls_p(P a, P b, P c) {
	if(dot(b-a, c-a) < EPS) return abs(c-a);
	if(dot(a-b, c-b) < EPS) return abs(c-b);
	return abs(cross(b-a, c-a))/abs(b-a);
}

bool is_inner_circle_ls(P w, double r, P a, P b) {
	if(LT(dist(w, a), r) && LT(dist(w, b), r)) {
		return true;
	}
	return false;
}

bool is_cross_circle_ls(P w, double r, P a, P b) {
	if(is_inner_circle_ls(w, r, a, b)) {
		return false;
	} else {
		if(LE(distance_ls_p(a, b, w), r)) {
			return true;
		}
	}
	return false;
}

int main() {
	int n;
	while(cin >> n, n) {
		vp w(n);
		vd r(n);
		double x, y;
		REP(i, n) {
			cin >> x >> y >> r[i];
			w[i] = P(x, y);
		}

		int m;
		cin >> m;
		REP(i, m) {
			P t, s;
			cin >> x >> y;
			t = P(x, y);
			cin >> x >> y;
			s = P(x, y);

			bool safe = false;
			REP(i, n) {
				if(is_cross_circle_ls(w[i], r[i], t, s)) {
					safe = true;
					break;
				}
			}

			cout << (safe ? "Safe" : "Danger") << endl;
		}
	}

	return 0;
}