Go: package main

import (
	"fmt"
	"math"
)

func main() {
	var n int
	fmt.Scan(&n)
	for i := 0; i < n; i++ {
		var xa, ya, ra, xb, yb, rb float64
		fmt.Scan(&xa, &ya, &ra, &xb, &yb, &rb)
		// println(xa, ya, ra, xb, yb, rb)
		dis := math.Sqrt((xa-xb)*(xa-xb) + (ya-yb)*(ya-yb))
		if dis + ra < rb {
			fmt.Println(-2)
		} else if dis + rb < ra {
			fmt.Println(2)
		} else if dis > rb + ra {
			fmt.Println(0)
		} else {
			fmt.Println(1)
		}
	}
}

C++: #include <iostream>
#include <cmath>
using namespace std;

int main(){
  int n;
  cin>>n;
  float xa,ya,ra,xb,yb,rb;
  while(n--){
    cin>>xa>>ya>>ra>>xb>>yb>>rb;
    float r;
    r = sqrt((xa-xb)*(xa-xb)+(ya-yb)*(ya-yb));
    if(r+rb<ra) cout<<"2"<<endl;
    else if(r+ra<rb) cout<<"-2"<<endl;
    else if(r>ra+rb) cout<<"0"<<endl;
    else cout<<"1"<<endl;
  }
  return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define all(a) (a).begin(),(a).end()
#define pb emplace_back
#define INF (1e9+1)

double dir(double x1, double y1, double x2, double y2){
    return hypot(abs(x1-x2),abs(y1-y2));
}

int main(){
    assert(dir(0,0,2,0)==2);
    int n;
    cin>>n;
    rep(loop,n){
        double x[2], y[2], r[2];
        rep(i,2)cin>>x[i]>>y[i]>>r[i];
        
        double direct = dir(x[0],y[0],x[1],y[1]);
        if(direct>r[0]+r[1])cout<<0<<endl;
        else if(direct+r[1]<=r[0])cout<<2<<endl;
        else if(direct+r[0]<=r[1])cout<<-2<<endl;
        else cout<<1<<endl;
    }
}

C++: #include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <cmath>
#include <cassert>

using namespace std;


#define all(c) ((c).begin()), ((c).end())
#define debug(c) cerr << "> " << #c << " = " << (c) << endl;
#define iter(c) __typeof((c).begin())
#define present(c, e) ((c).find((e)) != (c).end())
#define cpresent(c, e) (find(all(c), (e)) != (c).end())
#define tr(i, c) for (iter(c) i = (c).begin(); i != (c).end(); i++)
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define REP(i, a, b) for (int i = (int)(a); i <= (int)(b); i++)

#define mp make_pair
#define fst first
#define snd second
#define pb push_back


const double EPS = 1e-10;


typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
typedef complex<double> P;


struct C{
	P p;
	double r;
};

vector<P> isCC(const C &c1, const C &c2) {
	double d = abs(c1.p - c2.p);
	if (c1.r + c2.r - d < -EPS || fabs(c1.r - c2.r) - d > EPS) return vector<P>();
	double x = (d*d + c1.r * c1.r - c2.r * c2.r) / (2 * d);
	double y = sqrt(c1.r * c1.r - x * x);
	P diff = (c2.p - c1.p) / d;
	vector<P> res;
	res.pb(c1.p + diff * P(x, y));
	if (y != 0) res.pb(c1.p + diff * P(x, -y));
	return res;
}

int main(){
	int n; cin >> n;
	while (n--) {
		double xa, ya, ra, xb, yb, rb; cin >> xa >> ya >> ra >> xb >> yb >> rb;
		P pa = P(xa, ya), pb = P(xb, yb);
		C ca = (C){pa, ra}, cb = (C){pb, rb};
		int ans;
		if (isCC(ca, cb).size()){
			ans = 1;
		}
		else {
			if (ra + rb - abs(pa - pb) < -EPS) ans = 0;
			else ans = ra > rb ? 2 : -2;
		}
		cout << ans << endl;
	}
	
	return 0;
}

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

typedef long long int ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pair<int, int> > vii;
#define rrep(i, m, n) for(int (i)=(m); (i)<(n);  (i)++)
#define erep(i, m, n) for(int (i)=(m); (i)<=(n); (i)++)
#define  rep(i, n)    for(int (i)=0; (i)<(n);  (i)++)
#define rrev(i, m, n) for(int (i)=(n)-1; (i)>=(m); (i)--)
#define erev(i, m, n) for(int (i)=(n); (i)>=(m); (i)--)
#define  rev(i, n)    for(int (i)=(n)-1; (i)>=0; (i)--)
#define vrep(i, c)    for(__typeof((c).begin())i=(c).begin(); i!=(c).end(); i++)
#define  ALL(v)       (v).begin(), (v).end()
#define mp            make_pair
#define pb            push_back
template<class T, class S> inline bool minup(T& m, S x){ return m>(T)x ? (m=(T)x, true) : false; }
template<class T, class S> inline bool maxup(T& m, S x){ return m<(T)x ? (m=(T)x, true) : false; }

const int    INF = 1000000000;
const ll     MOD = 1000000007LL;
const double EPS = 1E-12;

template<typename T> T add(T x, T y){ if(abs(x+y) < EPS*(abs(x)+abs(y))) return 0; return x + y; }
template<typename T> inline bool semieq(T x, T y){ return abs(x - y) < EPS; }
template<typename T> inline bool semige(T x, T y){ return x - y > -EPS; }
template<typename T> inline bool semile(T x, T y){ return y - x > -EPS; }


struct Point : public complex<double>
{
public:
  Point() { this->real(0);  this->imag(0); }
  Point(const double& x, const double& y) { this->real(x);  this->imag(y); }
  Point(const complex<double> w)  { this->real(w.real());  this->imag(w.imag()); }
  inline double dot(Point p){ return (conj(*this) * p).real(); }  // ??????
  inline double det(Point p){ return (conj(*this) * p).imag(); }  // ??????
};

namespace std
{
  bool operator < (const Point& a, const Point& b)
  {
    return real(a) != real(b) ? real(a) < real(b) : imag(a) < imag(b);
  }
}
typedef vector<Point> Polygon;
#define currPoint(P, i) P[i]
#define nextPoint(P, i) P[(i+1)%P.size()]

struct Circle : Point
{
private:
  Point p;
  double r;

public:
  Circle(Point& p, double r) : p(p), r(r) {}
  Circle(double x, double y, double r) : p(Point(x, y)), r(r) {}
  inline Point center(){ return this->p; }
  inline double radius(){ return this->r; }
};

int circlesIntersection(Circle& A, Circle& B)
{
  double d = abs(A.center() - B.center());
  if(semile(d, A.radius() - B.radius())) return  1;  // B in A
  if(semile(d, B.radius() - A.radius())) return -1;  // A in B
  if(semieq(d, A.radius() - B.radius())) return  2;  // B in A????????\???
  if(semieq(d, B.radius() - A.radius())) return -2;  // A in B????????\???
  if(semige(d, A.radius() + B.radius())) return  3;  // ???????????????
  if(semieq(d, A.radius() + B.radius())) return -3;  // ?????\
  return 4;  // ????????£?????????
}

int n;
double x, y, r;

Point N(0.0, 0.0);

int main()
{
  cin >> n;

  while(n--){
    cin >> x >> y >> r;  Circle A(x, y, r);
    cin >> x >> y >> r;  Circle B(x, y, r);

    int res = circlesIntersection(A, B);
    if(res ==  1){ puts("2");   continue; }
    if(res == -1){ puts("-2");  continue; }
    if(res == -3){ puts("1");   continue; }
    if(res ==  3){ puts("0");   continue; }
  }

  return 0;
}

C++: #include <iostream>
#include <iomanip>
#include <vector>
#include <string>
#include <stack>
#include <set>
#include <cmath>
#include <algorithm>
using namespace std;

int main(){
	double xa , ya , ra , xb , yb , rb;
	double ab;
	int n;
	cin >> n;
	for(int i=0 ; i<n ; ++i){
		cin>> xa >> ya >> ra >> xb >> yb >> rb;
	ab=sqrt((xa-xb)*(xa-xb)+(ya-yb)*(ya-yb));
	if(ra-ab>rb) cout << 2 << endl;
	else if (rb-ab>ra) cout << -2 << endl;
	else if (ab>ra+ra) cout << 0 << endl;
	else cout << 1 << endl; 
	}
	return 0; 
}

C++: #include <iostream>
#include <cmath>

using namespace std;

inline double sq (double a) {
    return a * a;
}

inline double dist (double x1, double y1, double x2, double y2) {
    return sqrt(sq(x1 - x2) + sq(y1 - y2));
}

int main (void) {
    int N;
    cin >> N;
    while (N--) {
        double xa, ya, ra, xb, yb, rb;
        cin >> xa;
        cin >> ya;
        cin >> ra;
        cin >> xb;
        cin >> yb;
        cin >> rb;
        double d = dist(xa, ya, xb, yb);
        int s;
        if (d + rb < ra) s = 2;
        else if (d + ra < rb) s = -2;
        else if (d < ra + rb) s = 1;
        else s = 0;
        cout << s << endl;
    }
    return 0;
}