#include <iostream>
#include <math.h>
#include <cmath>
#include <algorithm>
#include <iomanip>
#include <queue>
#include <stack>
#include <climits>

using namespace std;
long n, m, a, b;
vector <vector <double>> mas;


struct ostrov {
   long x, y, r;
};

vector <ostrov> ostrov1;

void dk() {
    vector <bool> used(n);
    vector <double> l(n, INT_MAX);
    l[a] = 0;

    for (long i = 0; i < n; i++)
    {
        long min = INT_MAX;
        long s = INT_MIN;
        for (long j = 0; j < n; j++)
        {
            if (!used[j] && l[j] < min) {
                min = l[j];
                s = j;
            }
        }
        if (s == INT_MIN) break;

        for (long j = 0; j < n; j++){
            if (!used[j] && mas[s][j] != -1) {
                if (l[s] + mas[s][j] < l[j]) {
                    l[j] = l[s] + mas[s][j];
                }
            }
        }
        used[s] = true;
    }
    printf("%lf ", l[b]);

}


int main() {
   // freopen("input.txt", "r", stdin);
   // freopen("output.txt", "w", stdout);
    cin >> n;
    mas.resize(n); ostrov1.resize(n);

    for (long i = 0; i < n; i++){
        mas[i].resize(n);
        cin >> ostrov1[i].x >> ostrov1[i].y >> ostrov1[i].r;

    }
    for (long i = 0; i < n; i++) {
        for (long j = i + 1; j < n; j++){

            mas[i][j] =  mas[j][i] =sqrt(abs(ostrov1[i].x - ostrov1[j].x) * abs(ostrov1[i].x - ostrov1[j].x)
                + abs(ostrov1[i].y - ostrov1[j].y) * abs(ostrov1[i].y - ostrov1[j].y))
                - ostrov1[i].r - ostrov1[j].r;


        }
    }

    cin >> m;
    for (long i = 0; i < m; i++){
        cin >> a >> b;
        a--; b--;
        dk();
    }
}